text: /*
   * GUSEMU32 - API
   *
   * Copyright (C) 2000-2007 Tibor "TS" Schütz
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
   * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  
  #ifndef GUSEMU_H
  #define GUSEMU_H
  
  /* data types (need to be adjusted if neither a VC6 nor a C99 compatible compiler is used) */
  
  #if defined _WIN32 && defined _MSC_VER /* doesn't support other win32 compilers yet, do it yourself... */
   typedef unsigned char GUSbyte;
   typedef unsigned short GUSword;
   typedef unsigned int GUSdword;
   typedef signed char GUSchar;
   typedef signed short GUSsample;
  #else
   typedef int8_t GUSchar;
   typedef uint8_t GUSbyte;
   typedef uint16_t GUSword;
   typedef uint32_t GUSdword;
   typedef int16_t GUSsample;
  #endif
  
  typedef struct _GUSEmuState
  {
   GUSbyte *himemaddr; /* 1024*1024 bytes used for storing uploaded samples (+32 additional bytes for read padding) */
   GUSbyte *gusdatapos; /* (gusdataend-gusdata) bytes used for storing emulated GF1/mixer register states (32*32+4 bytes in initial GUSemu32 version) */
   uint32_t gusirq;
   uint32_t gusdma;
   unsigned int timer1fraction;
   unsigned int timer2fraction;
   void *opaque;
  } GUSEmuState;
  
  /* ** Callback functions needed: */
  /* NMI is defined as hwirq=-1 (not supported (yet?)) */
  /* GUS_irqrequest returns the number of IRQs actually scheduled into the virtual machine */
  /* Level triggered IRQ simulations normally return 1 */
  /* Event triggered IRQ simulation can safely ignore GUS_irqclear calls */
  int  GUS_irqrequest(GUSEmuState *state, int hwirq, int num);/* needed in both mixer and bus emulation functions. */
  void GUS_irqclear(  GUSEmuState *state, int hwirq); /* used by gus_write() only - can be left empty for mixer functions */
  void GUS_dmarequest(GUSEmuState *state);            /* used by gus_write() only - can be left empty for mixer functions */
  
  /* ** ISA bus interface functions: */
  
  /* Port I/O handlers */
  /* support the following ports: */
  /* 2x0,2x6,2x8...2xF,3x0...3x7;  */
  /* optional: 388,389 (at least writes should be forwarded or some GUS detection algorithms will fail) */
  /* data is passed in host byte order */
  unsigned int gus_read( GUSEmuState *state, int port, int size);
  void         gus_write(GUSEmuState *state, int port, int size, unsigned int data);
  /* size is given in bytes (1 for byte, 2 for word) */
  
  /* DMA data transfer function */
  /* data pointed to is passed in native x86 order */
  void gus_dma_transferdata(GUSEmuState *state, char *dma_addr, unsigned int count, int TC);
  /* Called back by GUS_start_DMA as soon as the emulated DMA controller is ready for a transfer to or from GUS */
  /* (might be immediately if the DMA controller was programmed first) */
  /* dma_addr is an already translated address directly pointing to the beginning of the memory block */
  /* do not forget to update DMA states after the call, including the DREQ and TC flags */
  /* it is possible to break down a single transfer into multiple ones, but take care that: */
  /* -dma_count is actually count-1 */
  /* -before and during a transfer, DREQ is set and TC cleared */
  /* -when calling gus_dma_transferdata(), TC is only set true for call transferring the last byte */
  /* -after the last transfer, DREQ is cleared and TC is set */
  
  /* ** GF1 mixer emulation functions: */
  /* Usually, gus_irqgen should be called directly after gus_mixvoices if you can meet the recommended ranges. */
  /* If the interrupts are executed immediately (i.e., are synchronous), it may be useful to break this */
  /* down into a sequence of gus_mixvoice();gus_irqgen(); calls while mixing an audio block. */
  /* If the interrupts are asynchronous, it may be needed to use a separate thread mixing into a temporary */
  /* audio buffer in order to avoid quality loss caused by large numsamples and elapsed_time values. */
  
  void gus_mixvoices(GUSEmuState *state, unsigned int playback_freq, unsigned int numsamples, GUSsample *bufferpos);
  /* recommended range: 10 < numsamples < 100 */
  /* lower values may result in increased rounding error, higher values often cause audible timing delays */
  
  void gus_irqgen(GUSEmuState *state, unsigned int elapsed_time);
  /* recommended range: 80us < elapsed_time < max(1000us, numsamples/playback_freq) */
  /* lower values won´t provide any benefit at all, higher values can cause audible timing delays */
  /* note: masked timers are also calculated by this function, thus it might be needed even without any IRQs in use! */
  
  #endif  /* gusemu.h */
  