external/mit/lua/dist/src/lzio.c

   1 /*      $NetBSD: lzio.c,v 1.1.1.2 2012/03/15 00:08:14 alnsn Exp $       */
   2
   3 /*
   4 ** $Id: lzio.c,v 1.1.1.2 2012/03/15 00:08:14 alnsn Exp $
   5 ** a generic input stream interface
   6 ** See Copyright Notice in lua.h
   7 */
   8
   9
  10 #include <string.h>
  11
  12 #define lzio_c
  13 #define LUA_CORE
  14
  15 #include "lua.h"
  16
  17 #include "llimits.h"
  18 #include "lmem.h"
  19 #include "lstate.h"
  20 #include "lzio.h"
  21
  22
  23 int luaZ_fill (ZIO *z) {
  24   size_t size;
  25   lua_State *L = z->L;
  26   const char *buff;
  27   lua_unlock(L);
  28   buff = z->reader(L, z->data, &size);
  29   lua_lock(L);
  30   if (buff == NULL || size == 0) return EOZ;
  31   z->n = size - 1;
  32   z->p = buff;
  33   return char2int(*(z->p++));
  34 }
  35
  36
  37 int luaZ_lookahead (ZIO *z) {
  38   if (z->n == 0) {
  39     if (luaZ_fill(z) == EOZ)
  40       return EOZ;
  41     else {
  42       z->n++;  /* luaZ_fill removed first byte; put back it */
  43       z->p--;
  44     }
  45   }
  46   return char2int(*z->p);
  47 }
  48
  49
  50 void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader, void *data) {
  51   z->L = L;
  52   z->reader = reader;
  53   z->data = data;
  54   z->n = 0;
  55   z->p = NULL;
  56 }
  57
  58
  59 /* --------------------------------------------------------------- read --- */
  60 size_t luaZ_read (ZIO *z, void *b, size_t n) {
  61   while (n) {
  62     size_t m;
  63     if (luaZ_lookahead(z) == EOZ)
  64       return n;  /* return number of missing bytes */
  65     m = (n <= z->n) ? n : z->n;  /* min. between n and z->n */
  66     memcpy(b, z->p, m);
  67     z->n -= m;
  68     z->p += m;
  69     b = (char *)b + m;
  70     n -= m;
  71   }
  72   return 0;
  73 }
  74
  75 /* ------------------------------------------------------------------------ */
  76 char *luaZ_openspace (lua_State *L, Mbuffer *buff, size_t n) {
  77   if (n > buff->buffsize) {
  78     if (n < LUA_MINBUFFER) n = LUA_MINBUFFER;
  79     luaZ_resizebuffer(L, buff, n);
  80   }
  81   return buff->buffer;
  82 }
  83
  84