src/lzio.c

   1 /*
   2 ** $Id: lzio.c,v 1.3 1997/12/22 20:57:18 roberto Exp $
   3 ** a generic input stream interface
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7
   8
   9 #include <stdio.h>
  10 #include <string.h>
  11
  12 #include "lzio.h"
  13
  14
  15
  16 /* ----------------------------------------------------- memory buffers --- */
  17
  18 static int zmfilbuf (ZIO* z)
  19 {
  20  return EOZ;
  21 }
  22
  23 ZIO* zmopen (ZIO* z, char* b, int size, char *name)
  24 {
  25  if (b==NULL) return NULL;
  26  z->n=size;
  27  z->p= (unsigned char *)b;
  28  z->filbuf=zmfilbuf;
  29  z->u=NULL;
  30  z->name=name;
  31  return z;
  32 }
  33
  34 /* ------------------------------------------------------------ strings --- */
  35
  36 ZIO* zsopen (ZIO* z, char* s, char *name)
  37 {
  38  if (s==NULL) return NULL;
  39  return zmopen(z,s,strlen(s),name);
  40 }
  41
  42 /* -------------------------------------------------------------- FILEs --- */
  43
  44 static int zffilbuf (ZIO* z)
  45 {
  46  int n=fread(z->buffer,1,ZBSIZE,z->u);
  47  if (n==0) return EOZ;
  48  z->n=n-1;
  49  z->p=z->buffer;
  50  return *(z->p++);
  51 }
  52
  53
  54 ZIO* zFopen (ZIO* z, FILE* f, char *name)
  55 {
  56  if (f==NULL) return NULL;
  57  z->n=0;
  58  z->p=z->buffer;
  59  z->filbuf=zffilbuf;
  60  z->u=f;
  61  z->name=name;
  62  return z;
  63 }
  64
  65
  66 /* --------------------------------------------------------------- read --- */
  67 int zread (ZIO *z, void *b, int n)
  68 {
  69   while (n) {
  70     int m;
  71     if (z->n == 0) {
  72       if (z->filbuf(z) == EOZ)
  73         return n;  /* retorna quantos faltaram ler */
  74       zungetc(z);  /* poe o resultado de filbuf no buffer */
  75     }
  76     m = (n <= z->n) ? n : z->n;  /* minimo de n e z->n */
  77     memcpy(b, z->p, m);
  78     z->n -= m;
  79     z->p += m;
  80     b = (char *)b + m;
  81     n -= m;
  82   }
  83   return 0;
  84 }