lzio.c

   1 /*
   2 ** $Id: lzio.c,v 1.31.1.1 2007/12/27 13:02:25 roberto Exp $
   3 ** a generic input stream interface
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7 #if 0
   8 #include <string.h>
   9 #endif
  10
  11 #define lzio_c
  12 #define LUA_CORE
  13
  14 #include "lua.h"
  15
  16 #include "llimits.h"
  17 #include "lmem.h"
  18 #include "lstate.h"
  19 #include "lzio.h"
  20
  21
  22 int luaZ_fill (ZIO *z) {
  23   size_t size;
  24   lua_State *L = z->L;
  25   const char *buff;
  26   lua_unlock(L);
  27   buff = z->reader(L, z->data, &size);
  28   lua_lock(L);
  29   if (buff == NULL || size == 0) return EOZ;
  30   z->n = size - 1;
  31   z->p = buff;
  32   return char2int(*(z->p++));
  33 }
  34
  35
  36 int luaZ_lookahead (ZIO *z) {
  37   if (z->n == 0) {
  38     if (luaZ_fill(z) == EOZ)
  39       return EOZ;
  40     else {
  41       z->n++;  /* luaZ_fill removed first byte; put back it */
  42       z->p--;
  43     }
  44   }
  45   return char2int(*z->p);
  46 }
  47
  48
  49 void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader, void *data) {
  50   z->L = L;
  51   z->reader = reader;
  52   z->data = data;
  53   z->n = 0;
  54   z->p = NULL;
  55 }
  56
  57
  58 /* --------------------------------------------------------------- read --- */
  59 size_t luaZ_read (ZIO *z, void *b, size_t n) {
  60   while (n) {
  61     size_t m;
  62     if (luaZ_lookahead(z) == EOZ)
  63       return n;  /* return number of missing bytes */
  64     m = (n <= z->n) ? n : z->n;  /* min. between n and z->n */
  65     memcpy(b, z->p, m);
  66     z->n -= m;
  67     z->p += m;
  68     b = (char *)b + m;
  69     n -= m;
  70   }
  71   return 0;
  72 }
  73
  74 /* ------------------------------------------------------------------------ */
  75 char *luaZ_openspace (lua_State *L, Mbuffer *buff, size_t n) {
  76   if (n > buff->buffsize) {
  77     if (n < LUA_MINBUFFER) n = LUA_MINBUFFER;
  78     luaZ_resizebuffer(L, buff, n);
  79   }
  80   return buff->buffer;
  81 }
  82
  83