1/*
2** $Id: lzio.c,v 1.37.1.1 2017/04/19 17:20:42 roberto Exp $
3** Buffered streams
4** See Copyright Notice in lua.h
5*/
6
7#define lzio_c
8#define LUA_CORE
9
10#include "lprefix.h"
11
12
13#include <string.h>
14
15#include "lua.h"
16
17#include "llimits.h"
18#include "lmem.h"
19#include "lstate.h"
20#include "lzio.h"
21
22
23int 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)
31 return EOZ;
32 z->n = size - 1; /* discount char being returned */
33 z->p = buff;
34 return cast_uchar(*(z->p++));
35}
36
37
38void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader, void *data) {
39 z->L = L;
40 z->reader = reader;
41 z->data = data;
42 z->n = 0;
43 z->p = NULL;
44}
45
46
47/* --------------------------------------------------------------- read --- */
48size_t luaZ_read (ZIO *z, void *b, size_t n) {
49 while (n) {
50 size_t m;
51 if (z->n == 0) { /* no bytes in buffer? */
52 if (luaZ_fill(z) == EOZ) /* try to read more */
53 return n; /* no more input; return number of missing bytes */
54 else {
55 z->n++; /* luaZ_fill consumed first byte; put it back */
56 z->p--;
57 }
58 }
59 m = (n <= z->n) ? n : z->n; /* min. between n and z->n */
60 memcpy(b, z->p, m);
61 z->n -= m;
62 z->p += m;
63 b = (char *)b + m;
64 n -= m;
65 }
66 return 0;
67}
68
69