src/lzio.c

   1 /*
   2 ** $Id: lzio.c,v 1.24 2003/03/20 16:00:56 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
  12 #include "lua.h"
  13
  14 #include "llimits.h"
  15 #include "lmem.h"
  16 #include "lzio.h"
  17
  18
  19 int luaZ_fill (ZIO *z) {
  20   size_t size;
  21   const char *buff = z->reader(NULL, z->data, &size);
  22   if (buff == NULL || size == 0) return EOZ;
  23   z->n = size - 1;
  24   z->p = buff;
  25   return char2int(*(z->p++));
  26 }
  27
  28
  29 int luaZ_lookahead (ZIO *z) {
  30   if (z->n == 0) {
  31     int c = luaZ_fill(z);
  32     if (c == EOZ) return c;
  33     z->n++;
  34     z->p--;
  35   }
  36   return char2int(*z->p);
  37 }
  38
  39
  40 void luaZ_init (ZIO *z, lua_Chunkreader reader, void *data, const char *name) {
  41   z->reader = reader;
  42   z->data = data;
  43   z->name = name;
  44   z->n = 0;
  45   z->p = NULL;
  46 }
  47
  48
  49 /* --------------------------------------------------------------- read --- */
  50 size_t luaZ_read (ZIO *z, void *b, size_t n) {
  51   while (n) {
  52     size_t m;
  53     if (z->n == 0) {
  54       if (luaZ_fill(z) == EOZ)
  55         return n;  /* return number of missing bytes */
  56       else {
  57         ++z->n;  /* filbuf removed first byte; put back it */
  58         --z->p;
  59       }
  60     }
  61     m = (n <= z->n) ? n : z->n;  /* min. between n and z->n */
  62     memcpy(b, z->p, m);
  63     z->n -= m;
  64     z->p += m;
  65     b = (char *)b + m;
  66     n -= m;
  67   }
  68   return 0;
  69 }
  70
  71 /* ------------------------------------------------------------------------ */
  72 char *luaZ_openspace (lua_State *L, Mbuffer *buff, size_t n) {
  73   if (n > buff->buffsize) {
  74     if (n < LUA_MINBUFFER) n = LUA_MINBUFFER;
  75     luaM_reallocvector(L, buff->buffer, buff->buffsize, n, char);
  76     buff->buffsize = n;
  77   }
  78   return buff->buffer;
  79 }
  80
  81