1 files changed, 97 insertions, 0 deletions
diff --git a/buildtools/endiangen.c b/buildtools/endiangen.c
new file mode 100644
index 00000000..07560c10
--- /dev/null
+++ b/buildtools/endiangen.c
@@ -0,0 +1,97 @@
+/*----------------------------------------------------------------------------
+                                 endiangen
+------------------------------------------------------------------------------
+  This is a program to create C code that declares the endianness of the
+  machine on which it is run.
+
+  It generates something like this:
+
+    #ifndef LITTLE_ENDIAN
+    #define LITTLE_ENDIAN 1234
+    #endif
+
+    #ifndef BIG_ENDIAN
+    #define BIG_ENDIAN 4321
+    #endif
+       
+    #ifndef BYTE_ORDER
+    #define BYTE_ORDER LITTLE_ENDIAN
+    #endif
+
+    #define BITS_PER_WORD 32
+    #endif
+
+    
+  Really good code usually is not sensitive to endianness.  But fast,
+  not-so-good code often is.  The best way for code to determine
+  endianness is for it to do a runtime cast of an integer to an array
+  of characters and see where the bytes land.  But if speed requires
+  even sleazier code than that, use these macros.
+
+-----------------------------------------------------------------------------*/
+#include <stdio.h>
+#include <unistd.h>
+
+#define MAX(a,b) ((a) > (b) ? (a) : (b))
+
+enum endianness {ENDIAN_LITTLE, ENDIAN_BIG};
+
+static enum endianness
+byteOrder(void) {
+    
+    enum endianness retval;
+
+    union {
+        unsigned char arrayval[2];
+        unsigned short numval;
+    } testunion;
+
+    testunion.numval = 3;
+
+    if (testunion.arrayval[0] == 3)
+        retval = ENDIAN_LITTLE;
+    else
+        retval = ENDIAN_BIG;
+
+    return retval;
+}
+
+
+
+static unsigned int
+bitsPerWord(void) {
+
+    return MAX(sizeof(long), sizeof(int)) * 8;
+}
+
+
+
+int
+main(int argc, char **argv) {
+
+    printf("/* This was generated by the program 'endiangen' */\n");
+    printf("\n");
+    printf("/* LITTLE_ENDIAN, BIG_ENDIAN, and BYTE_ORDER "
+           "may come from the C library\n");
+    printf("via ctype.h. */\n");
+    printf("#include <ctype.h>\n");
+    printf("#ifndef LITTLE_ENDIAN\n");
+    printf("#define LITTLE_ENDIAN 1234\n");
+    printf("#endif\n");
+    printf("#ifndef BIG_ENDIAN\n");
+    printf("#define BIG_ENDIAN 4321\n");
+    printf("#endif\n");
+    printf("\n");
+    printf("#ifndef BYTE_ORDER\n");
+    printf("#define BYTE_ORDER %s\n", 
+           byteOrder() == ENDIAN_LITTLE ? "LITTLE_ENDIAN" : "BIG_ENDIAN");
+    printf("#endif\n");
+    printf("\n");
+    printf("#define BITS_PER_WORD %u\n", bitsPerWord());
+
+    return 0;
+}
+
+
+
+