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      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 
     77