a generic input stream interface

lzio.c

@@ -0,0 +1,82 @@
+/*
+** $Id: zio.c,v 1.2 1997/06/20 19:25:54 roberto Exp $
+** a generic input stream interface
+** See Copyright Notice in lua.h
+*/
+
+
+
+#include <stdio.h>
+#include <string.h>
+
+#include "lzio.h"
+
+
+
+/* ----------------------------------------------------- memory buffers --- */
+
+static int zmfilbuf(ZIO* z)
+{
+ return EOZ;
+}
+
+ZIO* zmopen(ZIO* z, char* b, int size)
+{
+ if (b==NULL) return NULL;
+ z->n=size;
+ z->p= (unsigned char *)b;
+ z->filbuf=zmfilbuf;
+ z->u=NULL;
+ return z;
+}
+
+/* ------------------------------------------------------------ strings --- */
+
+ZIO* zsopen(ZIO* z, char* s)
+{
+ if (s==NULL) return NULL;
+ return zmopen(z,s,strlen(s));
+}
+
+/* -------------------------------------------------------------- FILEs --- */
+
+static int zffilbuf(ZIO* z)
+{
+ int n=fread(z->buffer,1,ZBSIZE,z->u);
+ if (n==0) return EOZ;
+ z->n=n-1;
+ z->p=z->buffer;
+ return *(z->p++);
+}
+
+
+ZIO* zFopen(ZIO* z, FILE* f)
+{
+ if (f==NULL) return NULL;
+ z->n=0;
+ z->p=z->buffer;
+ z->filbuf=zffilbuf;
+ z->u=f;
+ return z;
+}
+
+
+/* --------------------------------------------------------------- read --- */
+int zread(ZIO *z, void *b, int n)
+{
+  while (n) {
+    int m;
+    if (z->n == 0) {
+      if (z->filbuf(z) == EOZ)
+        return n;  /* retorna quantos faltaram ler */
+      zungetc(z);  /* poe o resultado de filbuf no buffer */
+    }
+    m = (n <= z->n) ? n : z->n;  /* minimo de n e z->n */
+    memcpy(b, z->p, m);
+    z->n -= m;
+    z->p += m;
+    b = (char *)b + m;
+    n -= m;
+  }
+  return 0;
+}