1 files changed, 86 insertions, 0 deletions
diff --git a/lib/util/intcode.h b/lib/util/intcode.h
new file mode 100644
index 00000000..4d9c83aa
--- /dev/null
+++ b/lib/util/intcode.h
@@ -0,0 +1,86 @@
+#ifndef INTCODE_H_INCLUDED
+#define INTCODE_H_INCLUDED
+
+#include "pm_config.h"  /* For uint32_t, BYTE_ORDER */
+
+typedef struct {
+/*----------------------------------------------------------------------------
+   This is a big-endian representation of a 32 bit integer.  I.e.
+   bytes[0] is the most significant 8 bits; bytes[3] is the least
+   significant 8 bits of the number in pure binary.
+
+   On a big-endian machines, this is bit for bit identical to uint32_t.
+   On a little-endian machine, it isn't.
+
+   This is an important data type because decent file formats use
+   big-endian -- they don't care if some CPU happens to use some other
+   code for its own work.
+-----------------------------------------------------------------------------*/
+    unsigned char bytes[4];
+} bigend32;
+
+
+unsigned int const pm_byteOrder = BYTE_ORDER;
+
+
+static __inline__ uint32_t
+pm_uintFromBigend32(bigend32 const arg) {
+
+    uint32_t retval;
+
+    switch (pm_byteOrder) {
+    case BIG_ENDIAN: {
+        union {
+            bigend32 bigend;
+            uint32_t native;
+        } converter;
+        
+        converter.bigend = arg;
+        
+        retval = converter.native;
+    }; break;
+    case LITTLE_ENDIAN: {
+        retval =
+            (arg.bytes[0] << 24) |
+            (arg.bytes[1] << 16) |
+            (arg.bytes[2] <<  8) |
+            (arg.bytes[3] <<  0);
+    } break;
+    }
+    return retval;
+}
+
+
+
+static __inline__ bigend32
+pm_bigendFromUint32(uint32_t const arg) {
+
+    bigend32 retval;
+
+    switch (pm_byteOrder) {
+    case BIG_ENDIAN: {
+        union {
+            bigend32 bigend;
+            uint32_t native;
+        } converter;
+        
+        converter.native = arg;
+
+        retval = converter.bigend;
+    } break;
+    case LITTLE_ENDIAN: {
+        uint32_t shift;
+        shift = arg;
+        retval.bytes[3] = shift;  /* Takes lower 8 bits */
+        shift >>= 8;
+        retval.bytes[2] = shift;  /* Takes lower 8 bits */
+        shift >>= 8;
+        retval.bytes[1] = shift;  /* Takes lower 8 bits */
+        shift >>= 8;
+        retval.bytes[0] = shift;  /* Takes lower 8 bits */
+    } break;
+    }
+    return retval;
+}
+
+#endif