lua/lzio.c

82 lines
1.6 KiB
C

/*
** $Id: lzio.c,v 1.15 2001/11/28 20:13:13 roberto Exp roberto $
** a generic input stream interface
** See Copyright Notice in lua.h
*/
#include <stdio.h>
#include <string.h>
#include "lua.h"
#include "lzio.h"
/* ----------------------------------------------------- memory buffers --- */
static int zmfilbuf (ZIO* z) {
(void)z; /* to avoid warnings */
return EOZ;
}
ZIO* zmopen (ZIO* z, const char* b, size_t size, const char *name) {
if (b==NULL) return NULL;
z->n = size;
z->p = (const unsigned char *)b;
z->filbuf = zmfilbuf;
z->u = NULL;
z->name = name;
return z;
}
/* -------------------------------------------------------------- FILEs --- */
static int zffilbuf (ZIO* z) {
size_t n;
if (feof((FILE *)z->u)) return EOZ;
n = fread(z->buffer, 1, ZBSIZE, (FILE *)z->u);
if (n==0) return EOZ;
z->n = n-1;
z->p = z->buffer;
return *(z->p++);
}
ZIO* zFopen (ZIO* z, FILE* f, const char *name) {
if (f==NULL) return NULL;
z->n = 0;
z->p = z->buffer;
z->filbuf = zffilbuf;
z->u = f;
z->name = name;
return z;
}
/* --------------------------------------------------------------- read --- */
size_t zread (ZIO *z, void *b, size_t n) {
while (n) {
size_t m;
if (z->n == 0) {
if (z->filbuf(z) == EOZ)
return n; /* return number of missing bytes */
else {
++z->n; /* filbuf removed first byte; put back it */
--z->p;
}
}
m = (n <= z->n) ? n : z->n; /* min. between n and z->n */
memcpy(b, z->p, m);
z->n -= m;
z->p += m;
b = (char *)b + m;
n -= m;
}
return 0;
}