liblua/lzio.c

   1 /*
   2 ** $Id: lzio.c,v 1.35 2012/05/14 13:34:18 roberto Exp $
   3 ** Buffered streams
   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)
  29     return EOZ;
  30   z->n = size - 1;  /* discount char being returned */
  31   z->p = buff;
  32   return cast_uchar(*(z->p++));
  33 }
  34
  35
  36 void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader, void *data) {
  37   z->L = L;
  38   z->reader = reader;
  39   z->data = data;
  40   z->n = 0;
  41   z->p = NULL;
  42 }
  43
  44
  45 /* --------------------------------------------------------------- read --- */
  46 size_t luaZ_read (ZIO *z, void *b, size_t n) {
  47   while (n) {
  48     size_t m;
  49     if (z->n == 0) {  /* no bytes in buffer? */
  50       if (luaZ_fill(z) == EOZ)  /* try to read more */
  51         return n;  /* no more input; return number of missing bytes */
  52       else {
  53         z->n++;  /* luaZ_fill consumed first byte; put it back */
  54         z->p--;
  55       }
  56     }
  57     m = (n <= z->n) ? n : z->n;  /* min. between n and z->n */
  58     memcpy(b, z->p, m);
  59     z->n -= m;
  60     z->p += m;
  61     b = (char *)b + m;
  62     n -= m;
  63   }
  64   return 0;
  65 }
  66
  67 /* ------------------------------------------------------------------------ */
  68 char *luaZ_openspace (lua_State *L, Mbuffer *buff, size_t n) {
  69   if (n > buff->buffsize) {
  70     if (n < LUA_MINBUFFER) n = LUA_MINBUFFER;
  71     luaZ_resizebuffer(L, buff, n);
  72   }
  73   return buff->buffer;
  74 }
  75
  76