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

   1 /*      $NetBSD: lzio.c,v 1.3 2015/02/02 14:03:05 lneto Exp $   */
   2
   3 /*
   4 ** Id: lzio.c,v 1.36 2014/11/02 19:19:04 roberto Exp
   5 ** Buffered streams
   6 ** See Copyright Notice in lua.h
   7 */
   8
   9 #define lzio_c
  10 #define LUA_CORE
  11
  12 #include "lprefix.h"
  13
  14
  15 #ifndef _KERNEL
  16 #include <string.h>
  17 #endif
  18
  19 #include "lua.h"
  20
  21 #include "llimits.h"
  22 #include "lmem.h"
  23 #include "lstate.h"
  24 #include "lzio.h"
  25
  26
  27 int luaZ_fill (ZIO *z) {
  28   size_t size;
  29   lua_State *L = z->L;
  30   const char *buff;
  31   lua_unlock(L);
  32   buff = z->reader(L, z->data, &size);
  33   lua_lock(L);
  34   if (buff == NULL || size == 0)
  35     return EOZ;
  36   z->n = size - 1;  /* discount char being returned */
  37   z->p = buff;
  38   return cast_uchar(*(z->p++));
  39 }
  40
  41
  42 void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader, void *data) {
  43   z->L = L;
  44   z->reader = reader;
  45   z->data = data;
  46   z->n = 0;
  47   z->p = NULL;
  48 }
  49
  50
  51 /* --------------------------------------------------------------- read --- */
  52 size_t luaZ_read (ZIO *z, void *b, size_t n) {
  53   while (n) {
  54     size_t m;
  55     if (z->n == 0) {  /* no bytes in buffer? */
  56       if (luaZ_fill(z) == EOZ)  /* try to read more */
  57         return n;  /* no more input; return number of missing bytes */
  58       else {
  59         z->n++;  /* luaZ_fill consumed first byte; put it back */
  60         z->p--;
  61       }
  62     }
  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