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1866
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1 /*
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2 ** $Id: lzio.c,v 1.35 2012/05/14 13:34:18 roberto Exp $
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3 ** Buffered streams
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4 ** See Copyright Notice in lua.h
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5 */
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6
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7
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8 #include <string.h>
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9
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10 #define lzio_c
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11 #define LUA_CORE
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12
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13 #include "lua.h"
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14
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15 #include "llimits.h"
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16 #include "lmem.h"
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17 #include "lstate.h"
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18 #include "lzio.h"
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19
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20
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21 int luaZ_fill (ZIO *z) {
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22 size_t size;
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23 lua_State *L = z->L;
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24 const char *buff;
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25 lua_unlock(L);
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26 buff = z->reader(L, z->data, &size);
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27 lua_lock(L);
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28 if (buff == NULL || size == 0)
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29 return EOZ;
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30 z->n = size - 1; /* discount char being returned */
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31 z->p = buff;
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32 return cast_uchar(*(z->p++));
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33 }
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34
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35
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36 void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader, void *data) {
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37 z->L = L;
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38 z->reader = reader;
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39 z->data = data;
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40 z->n = 0;
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41 z->p = NULL;
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42 }
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43
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44
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45 /* --------------------------------------------------------------- read --- */
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46 size_t luaZ_read (ZIO *z, void *b, size_t n) {
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47 while (n) {
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48 size_t m;
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49 if (z->n == 0) { /* no bytes in buffer? */
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50 if (luaZ_fill(z) == EOZ) /* try to read more */
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51 return n; /* no more input; return number of missing bytes */
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52 else {
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53 z->n++; /* luaZ_fill consumed first byte; put it back */
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54 z->p--;
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55 }
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56 }
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57 m = (n <= z->n) ? n : z->n; /* min. between n and z->n */
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58 memcpy(b, z->p, m);
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59 z->n -= m;
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60 z->p += m;
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61 b = (char *)b + m;
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62 n -= m;
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63 }
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64 return 0;
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65 }
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66
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67 /* ------------------------------------------------------------------------ */
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68 char *luaZ_openspace (lua_State *L, Mbuffer *buff, size_t n) {
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69 if (n > buff->buffsize) {
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70 if (n < LUA_MINBUFFER) n = LUA_MINBUFFER;
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71 luaZ_resizebuffer(L, buff, n);
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72 }
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73 return buff->buffer;
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74 }
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75
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76
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