Here's something I picked up from, I believe, this very newsgroup not long
back:
------------- macros.h: ---------------------------------
/*
macros.h:
Binary constant generator macro
By Tom Torfs - donated to the public domain
*/
/* All macro's evaluate to compile-time constants */
/* *** helper macros *** */
/* turn a numeric literal into a hex constant
(avoids problems with leading zeroes)
8-bit constants max value 0x11111111, always fits in unsigned long
*/
#define HEX__(n) 0x##n##LU
/* 8-bit conversion function */
#define B8__(x) ((x&0x0000000FLU)?1:0) \
+((x&0x000000F0LU)?2:0) \
+((x&0x00000F00LU)?4:0) \
+((x&0x0000F000LU)?8:0) \
+((x&0x000F0000LU)?16:0) \
+((x&0x00F00000LU)?32:0) \
+((x&0x0F000000LU)?64:0) \
+((x&0xF0000000LU)?128:0)
/* *** user macros *** */
/* for upto 8-bit binary constants */
#define B8(d) ((unsigned char)B8__(HEX__(d)))
/* for upto 16-bit binary constants, MSB first */
#define B16(dmsb,dlsb) (((unsigned short)B8(dmsb)<<8) \
+ B8(dlsb))
/* for upto 32-bit binary constants, MSB first */
#define B32(dmsb,db2,db3,dlsb) (((unsigned long)B8(dmsb)<<24) \
+ ((unsigned long)B8(db2)<<16) \
+ ((unsigned long)B8(db3)<<8) \
+ B8(dlsb))
/* Sample usage:
B8(01010101) = 85
B16(10101010,01010101) = 43605
B32(10000000,11111111,10101010,01010101) = 2164238933
*/
------------ test.c ---------------------
#include <stdio.h>
#include "macros.h"
int main()
{
int i = B8(1010);
int j = B8(10000000);
printf("i = %d, j = %d\n", i, j);
return 0;
}
HTH,
-leor
--
Leor Zolman --- BD Software ---
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