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