text: /*****************************************************************************/
  /*                                                                           */
  /*                                 codeseg.c                                 */
  /*                                                                           */
  /*                          Code segment structure                           */
  /*                                                                           */
  /*                                                                           */
  /*                                                                           */
  /* (C) 2001-2011, Ullrich von Bassewitz                                      */
  /*                Roemerstrasse 52                                           */
  /*                D-70794 Filderstadt                                        */
  /* EMail:         uz@cc65.org                                                */
  /*                                                                           */
  /*                                                                           */
  /* This software is provided 'as-is', without any expressed or implied       */
  /* warranty.  In no event will the authors be held liable for any damages    */
  /* arising from the use of this software.                                    */
  /*                                                                           */
  /* Permission is granted to anyone to use this software for any purpose,     */
  /* including commercial applications, and to alter it and redistribute it    */
  /* freely, subject to the following restrictions:                            */
  /*                                                                           */
  /* 1. The origin of this software must not be misrepresented; you must not   */
  /*    claim that you wrote the original software. If you use this software   */
  /*    in a product, an acknowledgment in the product documentation would be  */
  /*    appreciated but is not required.                                       */
  /* 2. Altered source versions must be plainly marked as such, and must not   */
  /*    be misrepresented as being the original software.                      */
  /* 3. This notice may not be removed or altered from any source              */
  /*    distribution.                                                          */
  /*                                                                           */
  /*****************************************************************************/
  
  
  
  #include <string.h>
  #include <ctype.h>
  
  /* common */
  #include "chartype.h"
  #include "check.h"
  #include "debugflag.h"
  #include "global.h"
  #include "hashfunc.h"
  #include "strbuf.h"
  #include "strutil.h"
  #include "xmalloc.h"
  
  /* cc65 */
  #include "asmlabel.h"
  #include "codeent.h"
  #include "codeinfo.h"
  #include "codeseg.h"
  #include "datatype.h"
  #include "error.h"
  #include "global.h"
  #include "ident.h"
  #include "output.h"
  #include "symentry.h"
  
  
  
  /*****************************************************************************/
  /*                             Helper functions                              */
  /*****************************************************************************/
  
  
  
  static void CS_PrintFunctionHeader (const CodeSeg* S)
  /* Print a comment with the function signature to the output file */
  {
      /* Get the associated function */
      const SymEntry* Func = S->Func;
  
      /* If this is a global code segment, do nothing */
      if (Func) {
          WriteOutput ("; ---------------------------------------------------------------\n"
                       "; ");
          PrintFuncSig (OutputFile, Func->Name, Func->Type);
          WriteOutput ("\n"
                       "; ---------------------------------------------------------------\n"
                       "\n");
      }
  }
  
  
  
  static void CS_MoveLabelsToEntry (CodeSeg* S, CodeEntry* E)
  /* Move all labels from the label pool to the given entry and remove them
  ** from the pool.
  */
  {
      /* Transfer the labels if we have any */
      unsigned I;
      unsigned LabelCount = CollCount (&S->Labels);
      for (I = 0; I < LabelCount; ++I) {
  
          /* Get the label */
          CodeLabel* L = CollAt (&S->Labels, I);
  
          /* Attach it to the entry */
          CE_AttachLabel (E, L);
      }
  
      /* Delete the transfered labels */
      CollDeleteAll (&S->Labels);
  }
  
  
  
  static void CS_MoveLabelsToPool (CodeSeg* S, CodeEntry* E)
  /* Move the labels of the code entry E to the label pool of the code segment */
  {
      unsigned LabelCount = CE_GetLabelCount (E);
      while (LabelCount--) {
          CodeLabel* L = CE_GetLabel (E, LabelCount);
          L->Owner = 0;
          CollAppend (&S->Labels, L);
      }
      CollDeleteAll (&E->Labels);
  }
  
  
  
  static CodeLabel* CS_FindLabel (CodeSeg* S, const char* Name, unsigned Hash)
  /* Find the label with the given name. Return the label or NULL if not found */
  {
      /* Get the first hash chain entry */
      CodeLabel* L = S->LabelHash[Hash];
  
      /* Search the list */
      while (L) {
          if (strcmp (Name, L->Name) == 0) {
              /* Found */
              break;
          }
          L = L->Next;
      }
      return L;
  }
  
  
  
  static CodeLabel* CS_NewCodeLabel (CodeSeg* S, const char* Name, unsigned Hash)
  /* Create a new label and insert it into the label hash table */
  {
      /* Create a new label */
      CodeLabel* L = NewCodeLabel (Name, Hash);
  
      /* Enter the label into the hash table */
      L->Next = S->LabelHash[L->Hash];
      S->LabelHash[L->Hash] = L;
  
      /* Return the new label */
      return L;
  }
  
  
  
  static void CS_RemoveLabelFromHash (CodeSeg* S, CodeLabel* L)
  /* Remove the given code label from the hash list */
  {
      /* Get the first entry in the hash chain */
      CodeLabel* List = S->LabelHash[L->Hash];
      CHECK (List != 0);
  
      /* First, remove the label from the hash chain */
      if (List == L) {
          /* First entry in hash chain */
          S->LabelHash[L->Hash] = L->Next;
      } else {
          /* Must search through the chain */
          while (List->Next != L) {
              /* If we've reached the end of the chain, something is *really* wrong */
              CHECK (List->Next != 0);
              /* Next entry */
              List = List->Next;
          }
          /* The next entry is the one, we have been searching for */
          List->Next = L->Next;
      }
  }
  
  
  
  static CodeLabel* PickRefLab (CodeEntry* E)
  /* Pick a reference label and move it to index 0 in E. */
  {
      unsigned I;
      unsigned LabelCount = CE_GetLabelCount (E);
      CHECK (LabelCount > 0);
      /* Use either the first one as reference label, or a label with a Ref that has no JumpTo.
      ** This is a hack to partially work around #1211.  Refs with no JumpTo are labels used
      ** in data segments.  (They are not tracked.)  If a data segment is the only reference,
      ** the label will be pruned away, but the data reference will remain, causing linking to fail.
      */
      CodeLabel* L0 = CE_GetLabel (E, 0);
      for (I = 1; I < LabelCount; ++I) {
          unsigned J;
          CodeLabel* L = CE_GetLabel (E, I);
          unsigned RefCount = CL_GetRefCount (L);
          for (J = 0; J < RefCount; ++J) {
              CodeEntry* EJ = CL_GetRef (L, J);
              if (EJ->JumpTo == NULL) {
                  /* Move it to the beginning since it's simpler to handle the removal this way. */
                  CE_ReplaceLabel (E, L, 0);
                  CE_ReplaceLabel (E, L0, I);
                  return L;
              }
          }
      }
      return L0;
  }
  
  
  
  /*****************************************************************************/
  /*                    Functions for parsing instructions                     */
  /*****************************************************************************/
  
  
  
  static const char* SkipSpace (const char* S)
  /* Skip white space and return an updated pointer */
  {
      while (IsSpace (*S)) {
          ++S;
      }
      return S;
  }
  
  
  
  static const char* ReadToken (const char* L, const char* Term,
                                char* Buf, unsigned BufSize)
  /* Read the next token into Buf, return the updated line pointer. The
  ** token is terminated by one of the characters given in term.
  */
  {
      /* Read/copy the token */
      unsigned I = 0;
      unsigned ParenCount = 0;
      while (*L && (ParenCount > 0 || strchr (Term, *L) == 0)) {
          if (I < BufSize-1) {
              Buf[I] = *L;
          } else if (I == BufSize-1) {
              /* Cannot store this character, this is an input error (maybe
              ** identifier too long or similar).
              */
              Error ("ASM code error: syntax error");
          }
          ++I;
          if (*L == ')') {
              --ParenCount;
          } else if (*L == '(') {
              ++ParenCount;
          }
          ++L;
      }
  
      /* Terminate the buffer contents */
      Buf[I] = '\0';
  
      /* Return the updated line pointer */
      return L;
  }
  
  
  
  static CodeEntry* ParseInsn (CodeSeg* S, LineInfo* LI, const char* L)
  /* Parse an instruction nnd generate a code entry from it. If the line contains
  ** errors, output an error message and return NULL.
  ** For simplicity, we don't accept the broad range of input a "real" assembler
  ** does. The instruction and the argument are expected to be separated by
  ** white space, for example.
  */
  {
      char                Mnemo[IDENTSIZE+10];
      const OPCDesc*      OPC;
      am_t                AM = 0;         /* Initialize to keep gcc silent */
      char                Arg[IDENTSIZE+10];
      char                Reg;
      CodeEntry*          E;
      CodeLabel*          Label;
  
      /* Read the first token and skip white space after it */
      L = SkipSpace (ReadToken (L, " \t:", Mnemo, sizeof (Mnemo)));
  
      /* Check if we have a label */
      if (*L == ':') {
  
          /* Skip the colon and following white space */
          L = SkipSpace (L+1);
  
          /* Add the label */
          CS_AddLabel (S, Mnemo);
  
          /* If we have reached end of line, bail out, otherwise a mnemonic
          ** may follow.
          */
          if (*L == '\0') {
              return 0;
          }
  
          L = SkipSpace (ReadToken (L, " \t", Mnemo, sizeof (Mnemo)));
      }
  
      /* Try to find the opcode description for the mnemonic */
      OPC = FindOP65 (Mnemo);
  
      /* If we didn't find the opcode, print an error and bail out */
      if (OPC == 0) {
          Error ("ASM code error: %s is not a valid mnemonic", Mnemo);
          return 0;
      }
  
      /* Get the addressing mode */
      Arg[0] = '\0';
      switch (*L) {
  
          case '\0':
              /* Implicit or accu */
              if (OPC->Info & OF_NOIMP) {
                  AM = AM65_ACC;
              } else {
                  AM = AM65_IMP;
              }
              break;
  
          case '#':
              /* Immidiate */
              StrCopy (Arg, sizeof (Arg), L+1);
              AM = AM65_IMM;
              break;
  
          case '(':
              /* Indirect */
              L = ReadToken (L+1, ",)", Arg, sizeof (Arg));
  
              /* Check for errors */
              if (*L == '\0') {
                  Error ("ASM code error: syntax error");
                  return 0;
              }
  
              /* Check the different indirect modes */
              if (*L == ',') {
                  /* Expect zp x indirect */
                  L = SkipSpace (L+1);
                  if (toupper (*L) != 'X') {
                      Error ("ASM code error: 'X' expected");
                      return 0;
                  }
                  L = SkipSpace (L+1);
                  if (*L != ')') {
                      Error ("ASM code error: ')' expected");
                      return 0;
                  }
                  L = SkipSpace (L+1);
                  if (*L != '\0') {
                      Error ("ASM code error: syntax error");
                      return 0;
                  }
                  AM = AM65_ZPX_IND;
              } else if (*L == ')') {
                  /* zp indirect or zp indirect, y */
                  L = SkipSpace (L+1);
                  if (*L == ',') {
                      L = SkipSpace (L+1);
                      if (toupper (*L) != 'Y') {
                          Error ("ASM code error: 'Y' expected");
                          return 0;
                      }
                      L = SkipSpace (L+1);
                      if (*L != '\0') {
                          Error ("ASM code error: syntax error");
                          return 0;
                      }
                      AM = AM65_ZP_INDY;
                  } else if (*L == '\0') {
                      AM = AM65_ZP_IND;
                  } else {
                      Error ("ASM code error: syntax error");
                      return 0;
                  }
              }
              break;
  
          case 'a':
          case 'A':
              /* Accumulator? */
              if (L[1] == '\0') {
                  AM = AM65_ACC;
                  break;
              }
              /* FALLTHROUGH */
  
          default:
              /* Absolute, maybe indexed */
              L = ReadToken (L, ",", Arg, sizeof (Arg));
              if (*L == '\0') {
                  /* Absolute, zeropage or branch */
                  if ((OPC->Info & OF_BRA) != 0) {
                      /* Branch */
                      AM = AM65_BRA;
                  } else if (IsZPArg (Arg)) {
                      AM = AM65_ZP;
                  } else {
                      /* Check for subroutine call to local label */
                      if ((OPC->Info & OF_CALL) && IsLocalLabelName (Arg)) {
                          Error ("ASM code error: "
                                 "Cannot use local label '%s' in subroutine call",
                                 Arg);
                      }
                      AM = AM65_ABS;
                  }
              } else if (*L == ',') {
                  /* Indexed */
                  L = SkipSpace (L+1);
                  if (*L == '\0') {
                      Error ("ASM code error: syntax error");
                      return 0;
                  } else {
                      Reg = toupper (*L);
                      L = SkipSpace (L+1);
                      if (Reg == 'X') {
                          if (IsZPArg (Arg)) {
                              AM = AM65_ZPX;
                          } else {
                              AM = AM65_ABSX;
                          }
                      } else if (Reg == 'Y') {
                          /* On 6502 only LDX and STX support AM65_ZPY.
                          ** We just play it simple and safe for now.
                          */
                          AM = AM65_ABSY;
                      } else {
                          Error ("ASM code error: syntax error");
                          return 0;
                      }
                      if (*L != '\0') {
                          Error ("ASM code error: syntax error");
                          return 0;
                      }
                  }
              }
              break;
  
      }
  
      /* If the instruction is a branch, check for the label and generate it
      ** if it does not exist. This may lead to unused labels (if the label
      ** is actually an external one) which are removed by the CS_MergeLabels
      ** function later.
      */
      Label = 0;
      if (AM == AM65_BRA) {
  
          /* Generate the hash over the label, then search for the label */
          unsigned Hash = HashStr (Arg) % CS_LABEL_HASH_SIZE;
          Label = CS_FindLabel (S, Arg, Hash);
  
          /* If we don't have the label, it's a forward ref - create it unless
          ** it's an external function.
          */
          if (Label == 0 && (OPC->OPC != OP65_JMP || IsLocalLabelName (Arg)) ) {
              /* Generate a new label */
              Label = CS_NewCodeLabel (S, Arg, Hash);
          }
      }
  
      /* We do now have the addressing mode in AM. Allocate a new CodeEntry
      ** structure and initialize it.
      */
      E = NewCodeEntry (OPC->OPC, AM, Arg, Label, LI);
  
      /* Return the new code entry */
      return E;
  }
  
  
  
  /*****************************************************************************/
  /*                                   Code                                    */
  /*****************************************************************************/
  
  
  
  CodeSeg* NewCodeSeg (const char* SegName, SymEntry* Func)
  /* Create a new code segment, initialize and return it */
  {
      unsigned I;
      const Type* RetType;
  
      /* Allocate memory */
      CodeSeg* S = xmalloc (sizeof (CodeSeg));
  
      /* Initialize the fields */
      S->SegName  = xstrdup (SegName);
      S->Func     = Func;
      InitCollection (&S->Entries);
      InitCollection (&S->Labels);
      for (I = 0; I < sizeof(S->LabelHash) / sizeof(S->LabelHash[0]); ++I) {
          S->LabelHash[I] = 0;
      }
  
      /* If we have a function given, get the return type of the function.
      ** Assume ANY return type besides void will use the A and X registers.
      */
      if (S->Func && !IsTypeVoid ((RetType = GetFuncReturn (Func->Type)))) {
          if (SizeOf (RetType) == SizeOf (type_long)) {
              S->ExitRegs = REG_EAX;
          } else {
              S->ExitRegs = REG_AX;
          }
      } else {
          S->ExitRegs = REG_NONE;
      }
  
      /* Copy the global optimization settings */
      S->Optimize       = (unsigned char) IS_Get (&Optimize);
      S->CodeSizeFactor = (unsigned) IS_Get (&CodeSizeFactor);
  
      /* Return the new struct */
      return S;
  }
  
  
  
  void CS_AddEntry (CodeSeg* S, struct CodeEntry* E)
  /* Add an entry to the given code segment */
  {
      /* Transfer the labels if we have any */
      CS_MoveLabelsToEntry (S, E);
  
      /* Add the entry to the list of code entries in this segment */
      CollAppend (&S->Entries, E);
  }
  
  
  
  void CS_AddVLine (CodeSeg* S, LineInfo* LI, const char* Format, va_list ap)
  /* Add a line to the given code segment */
  {
      const char* L;
      CodeEntry*  E;
      char        Token[IDENTSIZE+10];
  
      /* Format the line */
      StrBuf Buf = STATIC_STRBUF_INITIALIZER;
      SB_VPrintf (&Buf, Format, ap);
  
      /* Skip whitespace */
      L = SkipSpace (SB_GetConstBuf (&Buf));
  
      /* Check which type of instruction we have */
      E = 0;      /* Assume no insn created */
      switch (*L) {
  
          case '\0':
              /* Empty line, just ignore it */
              break;
  
          case ';':
              /* Comment or hint, ignore it for now */
              break;
  
          case '.':
              /* Control instruction */
              ReadToken (L, " \t", Token, sizeof (Token));
              Error ("ASM code error: Pseudo instruction '%s' not supported", Token);
              break;
  
          default:
              E = ParseInsn (S, LI, L);
              break;
      }
  
      /* If we have a code entry, transfer the labels and insert it */
      if (E) {
          CS_AddEntry (S, E);
      }
  
      /* Cleanup the string buffer */
      SB_Done (&Buf);
  }
  
  
  
  void CS_AddLine (CodeSeg* S, LineInfo* LI, const char* Format, ...)
  /* Add a line to the given code segment */
  {
      va_list ap;
      va_start (ap, Format);
      CS_AddVLine (S, LI, Format, ap);
      va_end (ap);
  }
  
  
  
  void CS_InsertEntry (CodeSeg* S, struct CodeEntry* E, unsigned Index)
  /* Insert the code entry at the index given. Following code entries will be
  ** moved to slots with higher indices.
  */
  {
      /* Insert the entry into the collection */
      CollInsert (&S->Entries, E, Index);
  }
  
  
  
  void CS_DelEntry (CodeSeg* S, unsigned Index)
  /* Delete an entry from the code segment. This includes moving any associated
  ** labels, removing references to labels and even removing the referenced labels
  ** if the reference count drops to zero.
  ** Note: Labels are moved forward if possible, that is, they are moved to the
  ** next insn (not the preceeding one).
  */
  {
      /* Get the code entry for the given index */
      CodeEntry* E = CS_GetEntry (S, Index);
  
      /* If the entry has a labels, we have to move this label to the next insn.
      ** If there is no next insn, move the label into the code segement label
      ** pool. The operation is further complicated by the fact that the next
      ** insn may already have a label. In that case change all reference to
      ** this label and delete the label instead of moving it.
      */
      unsigned Count = CE_GetLabelCount (E);
      if (Count > 0) {
  
          /* The instruction has labels attached. Check if there is a next
          ** instruction.
          */
          if (Index == CS_GetEntryCount (S)-1) {
  
              /* No next instruction, move to the codeseg label pool */
              CS_MoveLabelsToPool (S, E);
  
          } else {
  
              /* There is a next insn, get it */
              CodeEntry* N = CS_GetEntry (S, Index+1);
  
              /* Move labels to the next entry */
              CS_MoveLabels (S, E, N);
  
          }
      }
  
      /* If this insn references a label, remove the reference. And, if the
      ** the reference count for this label drops to zero, remove this label.
      */
      if (E->JumpTo) {
          /* Remove the reference */
          CS_RemoveLabelRef (S, E);
      }
  
      /* Delete the pointer to the insn */
      CollDelete (&S->Entries, Index);
  
      /* Delete the instruction itself */
      FreeCodeEntry (E);
  }
  
  
  
  void CS_DelEntries (CodeSeg* S, unsigned Start, unsigned Count)
  /* Delete a range of code entries. This includes removing references to labels,
  ** labels attached to the entries and so on.
  */
  {
      /* Start deleting the entries from the rear, because this involves less
      ** memory moving.
      */
      while (Count--) {
          CS_DelEntry (S, Start + Count);
      }
  }
  
  
  
  void CS_MoveEntries (CodeSeg* S, unsigned Start, unsigned Count, unsigned NewPos)
  /* Move a range of entries from one position to another. Start is the index
  ** of the first entry to move, Count is the number of entries and NewPos is
  ** the index of the target entry. The entry with the index Start will later
  ** have the index NewPos. All entries with indices NewPos and above are
  ** moved to higher indices. If the code block is moved to the end of the
  ** current code, and if pending labels exist, these labels will get attached
  ** to the first instruction of the moved block (the first one after the
  ** current code end)
  */
  {
      /* Transparently handle an empty range */
      if (Count == 0) {
          return;
      }
  
      /* If NewPos is at the end of the code segment, move any labels from the
      ** label pool to the first instruction of the moved range.
      */
      if (NewPos == CS_GetEntryCount (S)) {
          CS_MoveLabelsToEntry (S, CS_GetEntry (S, Start));
      }
  
      /* Move the code block to the destination */
      CollMoveMultiple (&S->Entries, Start, Count, NewPos);
  }
  
  
  
  struct CodeEntry* CS_GetPrevEntry (CodeSeg* S, unsigned Index)
  /* Get the code entry preceeding the one with the index Index. If there is no
  ** preceeding code entry, return NULL.
  */
  {
      if (Index == 0) {
          /* This is the first entry */
          return 0;
      } else {
          /* Previous entry available */
          return CollAtUnchecked (&S->Entries, Index-1);
      }
  }
  
  
  
  struct CodeEntry* CS_GetNextEntry (CodeSeg* S, unsigned Index)
  /* Get the code entry following the one with the index Index. If there is no
  ** following code entry, return NULL.
  */
  {
      if (Index >= CollCount (&S->Entries)-1) {
          /* This is the last entry */
          return 0;
      } else {
          /* Code entries left */
          return CollAtUnchecked (&S->Entries, Index+1);
      }
  }
  
  
  
  int CS_GetEntries (CodeSeg* S, struct CodeEntry** List,
                     unsigned Start, unsigned Count)
  /* Get Count code entries into List starting at index start. Return true if
  ** we got the lines, return false if not enough lines were available.
  */
  {
      /* Check if enough entries are available */
      if (Start + Count > CollCount (&S->Entries)) {
          return 0;
      }
  
      /* Copy the entries */
      while (Count--) {
          *List++ = CollAtUnchecked (&S->Entries, Start++);
      }
  
      /* We have the entries */
      return 1;
  }
  
  
  
  unsigned CS_GetEntryIndex (CodeSeg* S, struct CodeEntry* E)
  /* Return the index of a code entry */
  {
      int Index = CollIndex (&S->Entries, E);
      CHECK (Index >= 0);
      return Index;
  }
  
  
  
  int CS_RangeHasLabel (CodeSeg* S, unsigned Start, unsigned Count)
  /* Return true if any of the code entries in the given range has a label
  ** attached. If the code segment does not span the given range, check the
  ** possible span instead.
  */
  {
      unsigned EntryCount = CS_GetEntryCount(S);
  
      /* Adjust count. We expect at least Start to be valid. */
      CHECK (Start < EntryCount);
      if (Start + Count > EntryCount) {
          Count = EntryCount - Start;
      }
  
      /* Check each entry. Since we have validated the index above, we may
      ** use the unchecked access function in the loop which is faster.
      */
      while (Count--) {
          const CodeEntry* E = CollAtUnchecked (&S->Entries, Start++);
          if (CE_HasLabel (E)) {
              return 1;
          }
      }
  
      /* No label in the complete range */
      return 0;
  }
  
  
  
  CodeLabel* CS_AddLabel (CodeSeg* S, const char* Name)
  /* Add a code label for the next instruction to follow */
  {
      /* Calculate the hash from the name */
      unsigned Hash = HashStr (Name) % CS_LABEL_HASH_SIZE;
  
      /* Try to find the code label if it does already exist */
      CodeLabel* L = CS_FindLabel (S, Name, Hash);
  
      /* Did we find it? */
      if (L) {
          /* We found it - be sure it does not already have an owner */
          if (L->Owner) {
              Error ("ASM label '%s' is already defined", Name);
              return L;
          }
      } else {
          /* Not found - create a new one */
          L = CS_NewCodeLabel (S, Name, Hash);
      }
  
      /* Safety. This call is quite costly, but safety is better */
      if (CollIndex (&S->Labels, L) >= 0) {
          Error ("ASM label '%s' is already defined", Name);
          return L;
      }
  
      /* We do now have a valid label. Remember it for later */
      CollAppend (&S->Labels, L);
  
      /* Return the label */
      return L;
  }
  
  
  
  CodeLabel* CS_GenLabel (CodeSeg* S, struct CodeEntry* E)
  /* If the code entry E does already have a label, return it. Otherwise
  ** create a new label, attach it to E and return it.
  */
  {
      CodeLabel* L;
  
      if (CE_HasLabel (E)) {
  
          /* Get the label from this entry */
          L = CE_GetLabel (E, 0);
  
      } else {
  
          /* Get a new name */
          const char* Name = LocalLabelName (GetLocalLabel ());
  
          /* Generate the hash over the name */
          unsigned Hash = HashStr (Name) % CS_LABEL_HASH_SIZE;
  
          /* Create a new label */
          L = CS_NewCodeLabel (S, Name, Hash);
  
          /* Attach this label to the code entry */
          CE_AttachLabel (E, L);
  
      }
  
      /* Return the label */
      return L;
  }
  
  
  
  void CS_DelLabel (CodeSeg* S, CodeLabel* L)
  /* Remove references from this label and delete it. */
  {
      unsigned Count, I;
  
      /* First, remove the label from the hash chain */
      CS_RemoveLabelFromHash (S, L);
  
      /* Remove references from insns jumping to this label */
      Count = CollCount (&L->JumpFrom);
      for (I = 0; I < Count; ++I) {
          /* Get the insn referencing this label */
          CodeEntry* E = CollAt (&L->JumpFrom, I);
          /* Remove the reference */
          CE_ClearJumpTo (E);
      }
      CollDeleteAll (&L->JumpFrom);
  
      /* Remove the reference to the owning instruction if it has one. The
      ** function may be called for a label without an owner when deleting
      ** unfinished parts of the code. This is unfortunate since it allows
      ** errors to slip through.
      */
      if (L->Owner) {
          CollDeleteItem (&L->Owner->Labels, L);
      }
  
      /* All references removed, delete the label itself */
      FreeCodeLabel (L);
  }
  
  
  
  void CS_MergeLabels (CodeSeg* S)
  /* Merge code labels. That means: For each instruction, remove all labels but
  ** one and adjust references accordingly.
  */
  {
      unsigned I;
      unsigned J;
  
      /* First, remove all labels from the label symbol table that don't have an
      ** owner (this means that they are actually external labels but we didn't
      ** know that previously since they may have also been forward references).
      */
      for (I = 0; I < CS_LABEL_HASH_SIZE; ++I) {
  
          /* Get the first label in this hash chain */
          CodeLabel** L = &S->LabelHash[I];
          while (*L) {
              if ((*L)->Owner == 0) {
  
                  /* The label does not have an owner, remove it from the chain */
                  CodeLabel* X = *L;
                  *L = X->Next;
  
                  /* Cleanup any entries jumping to this label */
                  for (J = 0; J < CL_GetRefCount (X); ++J) {
                      /* Get the entry referencing this label */
                      CodeEntry* E = CL_GetRef (X, J);
                      /* And remove the reference. Do NOT call CE_ClearJumpTo
                      ** here, because this will also clear the label name,
                      ** which is not what we want.
                      */
                      E->JumpTo = 0;
                  }
  
                  /* Print some debugging output */
                  if (Debug) {
                      printf ("Removing unused global label '%s'", X->Name);
                  }
  
                  /* And free the label */
                  FreeCodeLabel (X);
              } else {
                  /* Label is owned, point to next code label pointer */
                  L = &((*L)->Next);
              }
          }
      }
  
      /* Walk over all code entries */
      for (I = 0; I < CS_GetEntryCount (S); ++I) {
  
          CodeLabel* RefLab;
          unsigned   J;
  
          /* Get a pointer to the next entry */
          CodeEntry* E = CS_GetEntry (S, I);
  
          /* If this entry has zero labels, continue with the next one */
          unsigned LabelCount = CE_GetLabelCount (E);
          if (LabelCount == 0) {
              continue;
          }
  
          /* Pick a label to keep, all references will be moved to this one, and the other labels
          ** will be deleted.  PickRefLab moves this to index 0.
          */
          RefLab = PickRefLab (E);
  
          /* Walk through the remaining labels and change references to these
          ** labels to a reference to the one and only label. Delete the labels
          ** that are no longer used. To increase performance, walk backwards
          ** through the list.
          */
          for (J = LabelCount-1; J >= 1; --J) {
  
              /* Get the next label */
              CodeLabel* L = CE_GetLabel (E, J);
  
              /* Move all references from this label to the reference label */
              CL_MoveRefs (L, RefLab);
  
              /* Remove the label completely. */
              CS_DelLabel (S, L);
          }
  
          /* The reference label is the only remaining label. Check if there
          ** are any references to this label, and delete it if this is not
          ** the case.
          */
          if (CollCount (&RefLab->JumpFrom) == 0) {
              /* Delete the label */
              CS_DelLabel (S, RefLab);
          }
      }
  }
  
  
  
  void CS_MoveLabels (CodeSeg* S, struct CodeEntry* Old, struct CodeEntry* New)
  /* Move all labels from Old to New. The routine will move the labels itself
  ** if New does not have any labels, and move references if there is at least
  ** a label for new. If references are moved, the old label is deleted
  ** afterwards.
  */
  {
      /* Get the number of labels to move */
      unsigned OldLabelCount = CE_GetLabelCount (Old);
  
      /* Does the new entry have itself a label? */
      if (CE_HasLabel (New)) {
  
          /* The new entry does already have a label - move references */
          CodeLabel* NewLabel = CE_GetLabel (New, 0);
          while (OldLabelCount--) {
  
              /* Get the next label */
              CodeLabel* OldLabel = CE_GetLabel (Old, OldLabelCount);
  
              /* Move references */
              CL_MoveRefs (OldLabel, NewLabel);
  
              /* Delete the label */
              CS_DelLabel (S, OldLabel);
  
          }
  
      } else {
  
          /* The new entry does not have a label, just move them */
          while (OldLabelCount--) {
  
              /* Move the label to the new entry */
              CE_MoveLabel (CE_GetLabel (Old, OldLabelCount), New);
  
          }
  
      }
  }
  
  
  
  void CS_RemoveLabelRef (CodeSeg* S, struct CodeEntry* E)
  /* Remove the reference between E and the label it jumps to. The reference
  ** will be removed on both sides and E->JumpTo will be 0 after that. If
  ** the reference was the only one for the label, the label will get
  ** deleted.
  */
  {
      /* Get a pointer to the label and make sure it exists */
      CodeLabel* L = E->JumpTo;
      CHECK (L != 0);
  
      /* Delete the entry from the label */
      CollDeleteItem (&L->JumpFrom, E);
  
      /* The entry jumps no longer to L */
      CE_ClearJumpTo (E);
  
      /* If there are no more references, delete the label */
      if (CollCount (&L->JumpFrom) == 0) {
          CS_DelLabel (S, L);
      }
  }
  
  
  
  void CS_MoveLabelRef (CodeSeg* S, struct CodeEntry* E, CodeLabel* L)
  /* Change the reference of E to L instead of the current one. If this
  ** was the only reference to the old label, the old label will get
  ** deleted.
  */
  {
      /* Get the old label */
      CodeLabel* OldLabel = E->JumpTo;
  
      /* Be sure that code entry references a label */
      PRECONDITION (OldLabel != 0);
  
      /* Remove the reference to our label */
      CS_RemoveLabelRef (S, E);
  
      /* Use the new label */
      CL_AddRef (L, E);
  }
  
  
  
  void CS_DelCodeRange (CodeSeg* S, unsigned First, unsigned Last)
  /* Delete all entries between first and last, both inclusive. The function
  ** can only handle basic blocks (First is the only entry, Last the only exit)
  ** and no open labels. It will call FAIL if any of these preconditions are
  ** violated.
  */
  {
      unsigned   I;
      CodeEntry* FirstEntry;
  
      /* Do some sanity checks */
      CHECK (First <= Last && Last < CS_GetEntryCount (S));
  
      /* If Last is actually the last insn, call CS_DelCodeAfter instead, which
      ** is more flexible in this case.
      */
      if (Last == CS_GetEntryCount (S) - 1) {
          CS_DelCodeAfter (S, First);
          return;
      }
  
      /* Get the first entry and check if it has any labels. If it has, move
      ** them to the insn following Last. If Last is the last insn of the code
      ** segment, make them ownerless and move them to the label pool.
      */
      FirstEntry = CS_GetEntry (S, First);
      if (CE_HasLabel (FirstEntry)) {
          /* Get the entry following last */
          CodeEntry* FollowingEntry = CS_GetNextEntry (S, Last);
          if (FollowingEntry) {
              /* There is an entry after Last - move the labels */
              CS_MoveLabels (S, FirstEntry, FollowingEntry);
          } else {
              /* Move the labels to the pool and clear the owner pointer */
              CS_MoveLabelsToPool (S, FirstEntry);
          }
      }
  
      /* First pass: Delete all references to labels. If the reference count
      ** for a label drops to zero, delete it.
      */
      for (I = Last; I >= First; --I) {
  
          /* Get the next entry */
          CodeEntry* E = CS_GetEntry (S, I);
  
          /* Check if this entry has a label reference */
          if (E->JumpTo) {
  
              /* If the label is a label in the label pool, this is an error */
              CodeLabel* L = E->JumpTo;
              CHECK (CollIndex (&S->Labels, L) < 0);
  
              /* Remove the reference to the label */
              CS_RemoveLabelRef (S, E);
          }
      }
  
      /* Second pass: Delete the instructions. If a label attached to an
      ** instruction still has references, it must be references from outside
      ** the deleted area, which is an error.
      */
      for (I = Last; I >= First; --I) {
  
          /* Get the next entry */
          CodeEntry* E = CS_GetEntry (S, I);
  
          /* Check if this entry has a label attached */
          CHECK (!CE_HasLabel (E));
  
          /* Delete the pointer to the entry */
          CollDelete (&S->Entries, I);
  
          /* Delete the entry itself */
          FreeCodeEntry (E);
      }
  }
  
  
  
  void CS_DelCodeAfter (CodeSeg* S, unsigned Last)
  /* Delete all entries including the given one */
  {
      /* Get the number of entries in this segment */
      unsigned Count = CS_GetEntryCount (S);
  
      /* First pass: Delete all references to labels. If the reference count
      ** for a label drops to zero, delete it.
      */
      unsigned C = Count;
      while (Last < C--) {
  
          /* Get the next entry */
          CodeEntry* E = CS_GetEntry (S, C);
  
          /* Check if this entry has a label reference */
          if (E->JumpTo) {
              /* If the label is a label in the label pool and this is the last
              ** reference to the label, remove the label from the pool.
              */
              CodeLabel* L = E->JumpTo;
              int Index = CollIndex (&S->Labels, L);
              if (Index >= 0 && CollCount (&L->JumpFrom) == 1) {
                  /* Delete it from the pool */
                  CollDelete (&S->Labels, Index);
              }
  
              /* Remove the reference to the label */
              CS_RemoveLabelRef (S, E);
          }
  
      }
  
      /* Second pass: Delete the instructions. If a label attached to an
      ** instruction still has references, it must be references from outside
      ** the deleted area. Don't delete the label in this case, just make it
      ** ownerless and move it to the label pool.
      */
      C = Count;
      while (Last < C--) {
  
          /* Get the next entry */
          CodeEntry* E = CS_GetEntry (S, C);
  
          /* Check if this entry has a label attached */
          if (CE_HasLabel (E)) {
              /* Move the labels to the pool and clear the owner pointer */
              CS_MoveLabelsToPool (S, E);
          }
  
          /* Delete the pointer to the entry */
          CollDelete (&S->Entries, C);
  
          /* Delete the entry itself */
          FreeCodeEntry (E);
      }
  }
  
  
  
  void CS_ResetMarks (CodeSeg* S, unsigned First, unsigned Last)
  /* Remove all user marks from the entries in the given range */
  {
      while (First <= Last) {
          CE_ResetMark (CS_GetEntry (S, First++));
      }
  }
  
  
  
  int CS_IsBasicBlock (CodeSeg* S, unsigned First, unsigned Last)
  /* Check if the given code segment range is a basic block. That is, check if
  ** First is the only entrance and Last is the only exit. This means that no
  ** jump/branch inside the block may jump to an insn below First or after(!)
  ** Last, and that no insn may jump into this block from the outside.
  */
  {
      unsigned I;
  
      /* Don't accept invalid ranges */
      CHECK (First <= Last);
  
      /* First pass: Walk over the range and remove all marks from the entries */
      CS_ResetMarks (S, First, Last);
  
      /* Second pass: Walk over the range checking all labels. Note: There may be
      ** label on the first insn which is ok.
      */
      I = First + 1;
      while (I <= Last) {
  
          /* Get the next entry */
          CodeEntry* E = CS_GetEntry (S, I);
  
          /* Check if this entry has one or more labels, if so, check which
          ** entries jump to this label.
          */
          unsigned LabelCount = CE_GetLabelCount (E);
          unsigned LabelIndex;
          for (LabelIndex = 0; LabelIndex < LabelCount; ++LabelIndex) {
  
              /* Get this label */
              CodeLabel* L = CE_GetLabel (E, LabelIndex);
  
              /* Walk over all entries that jump to this label. Check for each
              ** of the entries if it is out of the range.
              */
              unsigned RefCount = CL_GetRefCount (L);
              unsigned RefIndex;
              for (RefIndex = 0; RefIndex < RefCount; ++RefIndex) {
  
                  /* Get the code entry that jumps here */
                  CodeEntry* Ref = CL_GetRef (L, RefIndex);
  
                  /* Walk over out complete range and check if we find the
                  ** refering entry. This is cheaper than using CS_GetEntryIndex,
                  ** because CS_GetEntryIndex will search the complete code
                  ** segment and not just our range.
                  */
                  unsigned J;
                  for (J = First; J <= Last; ++J) {
                      if (Ref == CS_GetEntry (S, J)) {
                          break;
                      }
                  }
                  if (J > Last) {
                      /* We did not find the entry. This means that the jump to
                      ** out code segment entry E came from outside the range,
                      ** which in turn means that the given range is not a basic
                      ** block.
                      */
                      CS_ResetMarks (S, First, Last);
                      return 0;
                  }
  
                  /* If we come here, we found the entry. Mark it, so we know
                  ** that the branch to the label is in range.
                  */
                  CE_SetMark (Ref);
              }
          }
  
          /* Next entry */
          ++I;
      }
  
      /* Third pass: Walk again over the range and check all branches. If we
      ** find a branch that is not marked, its target is not inside the range
      ** (since we checked all the labels in the range before).
      */
      I = First;
      while (I <= Last) {
  
          /* Get the next entry */
          CodeEntry* E = CS_GetEntry (S, I);
  
          /* Check if this is a branch and if so, if it has a mark */
          if (E->Info & (OF_UBRA | OF_CBRA)) {
              if (!CE_HasMark (E)) {
                  /* No mark means not a basic block. Before bailing out, be sure
                  ** to remove the marks from the remaining entries.
                  */
                  CS_ResetMarks (S, I+1, Last);
                  return 0;
              }
  
              /* Remove the mark */
              CE_ResetMark (E);
          }
  
          /* Next entry */
          ++I;
      }
  
      /* Done - this is a basic block */
      return 1;
  }
  
  
  
  void CS_OutputPrologue (const CodeSeg* S)
  /* If the given code segment is a code segment for a function, output the
  ** assembler prologue into the file. That is: Output a comment header, switch
  ** to the correct segment and enter the local function scope. If the code
  ** segment is global, do nothing.
  */
  {
      /* Get the function associated with the code segment */
      SymEntry* Func = S->Func;
  
      /* If the code segment is associated with a function, print a function
      ** header and enter a local scope. Be sure to switch to the correct
      ** segment before outputing the function label.
      */
      if (Func) {
          /* Get the function descriptor */
          CS_PrintFunctionHeader (S);
          WriteOutput (".segment\t\"%s\"\n\n.proc\t_%s", S->SegName, Func->Name);
          if (IsQualNear (Func->Type)) {
              WriteOutput (": near");
          } else if (IsQualFar (Func->Type)) {
              WriteOutput (": far");
          }
          WriteOutput ("\n\n");
      }
  
  }
  
  
  
  void CS_OutputEpilogue (const CodeSeg* S)
  /* If the given code segment is a code segment for a function, output the
  ** assembler epilogue into the file. That is: Close the local function scope.
  */
  {
      if (S->Func) {
          WriteOutput (".endproc\n\n");
      }
  }
  
  
  
  void CS_Output (CodeSeg* S)
  /* Output the code segment data to the output file */
  {
      unsigned I;
      const LineInfo* LI;
  
      /* Get the number of entries in this segment */
      unsigned Count = CS_GetEntryCount (S);
  
      /* If the code segment is empty, bail out here */
      if (Count == 0) {
          return;
      }
  
      /* Generate register info */
      CS_GenRegInfo (S);
  
      /* Output the segment directive */
      WriteOutput (".segment\t\"%s\"\n\n", S->SegName);
  
      /* Output all entries, prepended by the line information if it has changed */
      LI = 0;
      for (I = 0; I < Count; ++I) {
          /* Get the next entry */
          const CodeEntry* E = CollConstAt (&S->Entries, I);
          /* Check if the line info has changed. If so, output the source line
          ** if the option is enabled and output debug line info if the debug
          ** option is enabled.
          */
          if (E->LI != LI) {
              /* Line info has changed, remember the new line info */
              LI = E->LI;
  
              /* Add the source line as a comment. Beware: When line continuation
              ** was used, the line may contain newlines.
              */
              if (AddSource) {
                  const char* L = LI->Line;
                  WriteOutput (";\n; ");
                  while (*L) {
                      const char* N = strchr (L, '\n');
                      if (N) {
                          /* We have a newline, just write the first part */
                          WriteOutput ("%.*s\n; ", (int) (N - L), L);
                          L = N+1;
                      } else {
                          /* No Newline, write as is */
                          WriteOutput ("%s\n", L);
                          break;
                      }
                  }
                  WriteOutput (";\n");
              }
  
              /* Add line debug info */
              if (DebugInfo) {
                  WriteOutput ("\t.dbg\tline, \"%s\", %u\n",
                               GetInputName (LI), GetInputLine (LI));
              }
          }
          /* Output the code */
          CE_Output (E);
      }
  
      /* Prettyier formatting */
      WriteOutput ("\n");
  
      /* If debug info is enabled, terminate the last line number information */
      if (DebugInfo) {
          WriteOutput ("\t.dbg\tline\n");
      }
  
      /* Free register info */
      CS_FreeRegInfo (S);
  }
  
  
  
  void CS_FreeRegInfo (CodeSeg* S)
  /* Free register infos for all instructions */
  {
      unsigned I;
      for (I = 0; I < CS_GetEntryCount (S); ++I) {
          CE_FreeRegInfo (CS_GetEntry(S, I));
      }
  }
  
  
  
  void CS_GenRegInfo (CodeSeg* S)
  /* Generate register infos for all instructions */
  {
      unsigned I;
      RegContents Regs;           /* Initial register contents */
      RegContents* CurrentRegs;   /* Current register contents */
      int WasJump;                /* True if last insn was a jump */
      int Done;                   /* All runs done flag */
  
      /* Be sure to delete all register infos */
      CS_FreeRegInfo (S);
  
      /* We may need two runs to get back references right */
      do {
  
          /* Assume we're done after this run */
          Done = 1;
  
          /* On entry, the register contents are unknown */
          RC_Invalidate (&Regs);
          RC_InvalidatePS (&Regs);
          CurrentRegs = &Regs;
  
          /* Walk over all insns and note just the changes from one insn to the
          ** next one.
          */
          WasJump = 0;
          for (I = 0; I < CS_GetEntryCount (S); ++I) {
  
              CodeEntry* P;
  
              /* Get the next instruction */
              CodeEntry* E = CollAtUnchecked (&S->Entries, I);
  
              /* If the instruction has a label, we need some special handling */
              unsigned LabelCount = CE_GetLabelCount (E);
              if (LabelCount > 0) {
  
                  /* Loop over all entry points that jump here. If these entry
                  ** points already have register info, check if all values are
                  ** known and identical. If all values are identical, and the
                  ** preceeding instruction was not an unconditional branch, check
                  ** if the register value on exit of the preceeding instruction
                  ** is also identical. If all these values are identical, the
                  ** value of a register is known, otherwise it is unknown.
                  */
                  CodeLabel* Label = CE_GetLabel (E, 0);
                  unsigned Entry;
                  if (WasJump) {
                      /* Preceeding insn was an unconditional branch */
                      CodeEntry* J = CL_GetRef(Label, 0);
                      if (J->RI) {
                          Regs = J->RI->Out2;
                      } else {
                          RC_Invalidate (&Regs);
                          RC_InvalidatePS (&Regs);
                      }
                      Entry = 1;
                  } else {
                      Regs = *CurrentRegs;
                      Entry = 0;
                  }
  
                  while (Entry < CL_GetRefCount (Label)) {
                      /* Get this entry */
                      CodeEntry* J = CL_GetRef (Label, Entry);
                      if (J->RI == 0) {
                          /* No register info for this entry. This means that the
                          ** instruction that jumps here is at higher addresses and
                          ** the jump is a backward jump. We need a second run to
                          ** get the register info right in this case. Until then,
                          ** assume unknown register contents.
                          */
                          Done = 0;
                          RC_Invalidate (&Regs);
                          RC_InvalidatePS (&Regs);
                          break;
                      }
                      if (J->RI->Out2.RegA != Regs.RegA) {
                          Regs.RegA = UNKNOWN_REGVAL;
                      }
                      if (J->RI->Out2.RegX != Regs.RegX) {
                          Regs.RegX = UNKNOWN_REGVAL;
                      }
                      if (J->RI->Out2.RegY != Regs.RegY) {
                          Regs.RegY = UNKNOWN_REGVAL;
                      }
                      if (J->RI->Out2.SRegLo != Regs.SRegLo) {
                          Regs.SRegLo = UNKNOWN_REGVAL;
                      }
                      if (J->RI->Out2.SRegHi != Regs.SRegHi) {
                          Regs.SRegHi = UNKNOWN_REGVAL;
                      }
                      if (J->RI->Out2.Tmp1 != Regs.Tmp1) {
                          Regs.Tmp1 = UNKNOWN_REGVAL;
                      }
                      unsigned PF = J->RI->Out2.PFlags ^ Regs.PFlags;
                      Regs.PFlags |= ((PF >> 8) | PF | (PF << 8)) & UNKNOWN_PFVAL_ALL;
                      Regs.ZNRegs &= J->RI->Out2.ZNRegs;
                      ++Entry;
                  }
  
                  /* Use this register info */
                  CurrentRegs = &Regs;
  
              }
  
              /* Generate register info for this instruction */
              CE_GenRegInfo (E, CurrentRegs);
  
              /* Remember for the next insn if this insn was an uncondition branch */
              WasJump = (E->Info & OF_UBRA) != 0;
  
              /* Output registers for this insn are input for the next */
              CurrentRegs = &E->RI->Out;
  
              /* If this insn is a branch on zero flag, we may have more info on
              ** register contents for one of both flow directions, but only if
              ** we've gone through a previous instruction.
              */
              if (LabelCount == 0 && (E->Info & OF_ZBRA) != 0 && (P = CS_GetPrevEntry (S, I)) != 0) {
  
                  /* Get the branch condition */
                  bc_t BC = GetBranchCond (E->OPC);
  
                  /* Check the previous instruction */
                  switch (P->OPC) {
  
                      case OP65_ADC:
                      case OP65_AND:
                      case OP65_DEA:
                      case OP65_EOR:
                      case OP65_INA:
                      case OP65_LDA:
                      case OP65_ORA:
                      case OP65_PLA:
                      case OP65_SBC:
                          /* A is zero in one execution flow direction */
                          if (BC == BC_EQ) {
                              E->RI->Out2.RegA = 0;
                          } else {
                              E->RI->Out.RegA = 0;
                          }
                          break;
  
                      case OP65_CMP:
                          /* If this is an immidiate compare, the A register has
                          ** the value of the compare later.
                          */
                          if (CE_IsConstImm (P)) {
                              if (BC == BC_EQ) {
                                  E->RI->Out2.RegA = (unsigned char)P->Num;
                              } else {
                                  E->RI->Out.RegA = (unsigned char)P->Num;
                              }
                          }
                          break;
  
                      case OP65_CPX:
                          /* If this is an immidiate compare, the X register has
                          ** the value of the compare later.
                          */
                          if (CE_IsConstImm (P)) {
                              if (BC == BC_EQ) {
                                  E->RI->Out2.RegX = (unsigned char)P->Num;
                              } else {
                                  E->RI->Out.RegX = (unsigned char)P->Num;
                              }
                          }
                          break;
  
                      case OP65_CPY:
                          /* If this is an immidiate compare, the Y register has
                          ** the value of the compare later.
                          */
                          if (CE_IsConstImm (P)) {
                              if (BC == BC_EQ) {
                                  E->RI->Out2.RegY = (unsigned char)P->Num;
                              } else {
                                  E->RI->Out.RegY = (unsigned char)P->Num;
                              }
                          }
                          break;
  
                      case OP65_DEX:
                      case OP65_INX:
                      case OP65_LDX:
                      case OP65_PLX:
                          /* X is zero in one execution flow direction */
                          if (BC == BC_EQ) {
                              E->RI->Out2.RegX = 0;
                          } else {
                              E->RI->Out.RegX = 0;
                          }
                          break;
  
                      case OP65_DEY:
                      case OP65_INY:
                      case OP65_LDY:
                      case OP65_PLY:
                          /* X is zero in one execution flow direction */
                          if (BC == BC_EQ) {
                              E->RI->Out2.RegY = 0;
                          } else {
                              E->RI->Out.RegY = 0;
                          }
                          break;
  
                      case OP65_TAX:
                      case OP65_TXA:
                          /* If the branch is a beq, both A and X are zero at the
                          ** branch target, otherwise they are zero at the next
                          ** insn.
                          */
                          if (BC == BC_EQ) {
                              E->RI->Out2.RegA = E->RI->Out2.RegX = 0;
                          } else {
                              E->RI->Out.RegA = E->RI->Out.RegX = 0;
                          }
                          break;
  
                      case OP65_TAY:
                      case OP65_TYA:
                          /* If the branch is a beq, both A and Y are zero at the
                          ** branch target, otherwise they are zero at the next
                          ** insn.
                          */
                          if (BC == BC_EQ) {
                              E->RI->Out2.RegA = E->RI->Out2.RegY = 0;
                          } else {
                              E->RI->Out.RegA = E->RI->Out.RegY = 0;
                          }
                          break;
  
                      default:
                          break;
  
                  }
              }
          }
      } while (!Done);
  
  }
  