Built error checking into file reading/writing routines and calls of them.

[plomrogue] / src / readwrite.c

diff --git a/src/readwrite.c b/src/readwrite.c
index 40fc63f0a5feb5c8f210e3c06a0060400cb80ab2..6d24992520b6687a99e91007231d1ec10c455651 100644 (file)
--- a/src/readwrite.c
+++ b/src/readwrite.c
@@ -6,40 +6,98 @@
 
 
 
-extern uint16_t read_uint16_bigendian(FILE * file)
+/* Read/write "x" from/to "file" as bigendian representation of "size" bits. */
+static uint8_t read_uintX_bigendian(FILE * file, uint32_t * x, uint8_t size);
+static uint8_t write_uintX_bigendian(FILE * file, uint32_t x, uint8_t size);
+
+
+
+static uint8_t read_uintX_bigendian(FILE * file, uint32_t * x, uint8_t size)
+{
+    if (0 != size % 8)
+    {
+        return 1;
+    }
+    int16_t bitshift = size - 8;
+
+    * x = 0;
+    int test;
+    for (; bitshift >= 0; bitshift = bitshift - 8)
+    {
+        test = fgetc(file);
+        if (EOF == test)
+        {
+            return 1;
+        }
+        * x = * x + ((uint32_t) test << bitshift);
+    }
+    return 0;
+}
+
+
+
+static uint8_t write_uintX_bigendian(FILE * file, uint32_t x, uint8_t size)
+{
+    if (0 != size % 8)
+    {
+        return 1;
+    }
+    int16_t bitshift = size - 8;
+
+    for (; bitshift >= 0; bitshift = bitshift - 8)
+    {
+        if (EOF == fputc((x >> bitshift) & 0xFF, file))
+        {
+            return 1;
+        }
+    }
+    return 0;
+}
+
+
+
+extern uint8_t read_uint8(FILE * file, uint8_t * x)
+{
+    uint32_t y = * x;
+    uint8_t fail = read_uintX_bigendian(file, &y, 8);
+    * x = (uint8_t) y;
+    return fail;
+}
+
+
+
+extern uint8_t read_uint16_bigendian(FILE * file, uint16_t * x)
+{
+    uint32_t y = * x;
+    uint8_t fail = read_uintX_bigendian(file, &y, 16);
+    * x = (uint16_t) y;
+    return fail;
+}
+
+
+
+extern uint8_t read_uint32_bigendian(FILE * file, uint32_t * x)
 {
-    uint16_t x;
-    x =     (uint16_t) fgetc(file) << 8;
-    x = x + (uint16_t) fgetc(file);
-    return x;
+    return read_uintX_bigendian(file, x, 32);
 }
 
 
 
-extern uint32_t read_uint32_bigendian(FILE * file)
+extern uint8_t write_uint8(uint8_t x, FILE * file)
 {
-    uint32_t x;
-    x =       (uint32_t) fgetc(file) << 24;
-    x = x + ( (uint32_t) fgetc(file) << 16 );
-    x = x + ( (uint32_t) fgetc(file) <<  8 );
-    x = x +   (uint32_t) fgetc(file);
-    return x;
+    return write_uintX_bigendian(file, x, 8);
 }
 
 
 
-extern void write_uint16_bigendian(uint16_t x, FILE * file)
+extern uint8_t write_uint16_bigendian(uint16_t x, FILE * file)
 {
-    fputc( x >> 8,   file );
-    fputc( x & 0xFF, file );
+    return write_uintX_bigendian(file, x, 16);
 }
 
 
 
-extern void write_uint32_bigendian(uint32_t x, FILE * file)
+extern uint8_t write_uint32_bigendian(uint32_t x, FILE * file)
 {
-    fputc(   x >> 24,          file);
-    fputc( ( x >> 16 ) & 0xFF, file);
-    fputc( ( x >>  8 ) & 0xFF, file);
-    fputc(   x         & 0xFF, file);
+    return write_uintX_bigendian(file, x, 32);
 }