1 /*
2 ** $Id: lzio.c $
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
luaZ_fill(ZIO * z)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)
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
luaZ_init(lua_State * L,ZIO * z,lua_Reader reader,void * data)38 void 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 --- */
luaZ_read(ZIO * z,void * b,size_t n)48 size_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