text: /*
  ** $Id: lzio.c,v 1.34 2011/07/15 12:35:32 roberto Exp $
  ** a generic input stream interface
  ** See Copyright Notice in lua.h
  */
  
  
  #include <string.h>
  
  #define lzio_c
  #define LUA_CORE
  
  #include "lua.h"
  
  #include "llimits.h"
  #include "lmem.h"
  #include "lstate.h"
  #include "lzio.h"
  
  
  int luaZ_fill (ZIO *z) {
    size_t size;
    lua_State *L = z->L;
    const char *buff;
    lua_unlock(L);
    buff = z->reader(L, z->data, &size);
    lua_lock(L);
    if (buff == NULL || size == 0)
      return EOZ;
    z->n = size - 1;  /* discount char being returned */
    z->p = buff;
    return cast_uchar(*(z->p++));
  }
  
  
  void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader, void *data) {
    z->L = L;
    z->reader = reader;
    z->data = data;
    z->n = 0;
    z->p = NULL;
  }
  
  
  /* --------------------------------------------------------------- read --- */
  size_t luaZ_read (ZIO *z, void *b, size_t n) {
    while (n) {
      size_t m;
      if (z->n == 0) {  /* no bytes in buffer? */
        if (luaZ_fill(z) == EOZ)  /* try to read more */
          return n;  /* no more input; return number of missing bytes */
        else {
          z->n++;  /* luaZ_fill consumed first byte; put it back */
          z->p--;
        }
      }
      m = (n <= z->n) ? n : z->n;  /* min. between n and z->n */
      memcpy(b, z->p, m);
      z->n -= m;
      z->p += m;
      b = (char *)b + m;
      n -= m;
    }
    return 0;
  }
  
  /* ------------------------------------------------------------------------ */
  char *luaZ_openspace (lua_State *L, Mbuffer *buff, size_t n) {
    if (n > buff->buffsize) {
      if (n < LUA_MINBUFFER) n = LUA_MINBUFFER;
      luaZ_resizebuffer(L, buff, n);
    }
    return buff->buffer;
  }
  
  
  