mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-28 21:49:33 +00:00
36 lines
650 B
C
36 lines
650 B
C
/*
|
|
* C library strlen routine
|
|
*
|
|
* This routine has been optimized for the CPU32+.
|
|
* It should run on all 68k machines.
|
|
*
|
|
* W. Eric Norum
|
|
* Saskatchewan Accelerator Laboratory
|
|
* University of Saskatchewan
|
|
* Saskatoon, Saskatchewan, CANADA
|
|
* eric@skatter.usask.ca
|
|
*/
|
|
|
|
#include <string.h>
|
|
|
|
/*
|
|
* Test bytes using CPU32+ loop mode if possible.
|
|
*/
|
|
size_t
|
|
strlen (const char *str)
|
|
{
|
|
unsigned int n = ~0;
|
|
const char *cp = str;
|
|
|
|
asm volatile ("1:\n"
|
|
"\ttst.b (%0)+\n"
|
|
#if defined(__mcpu32__)
|
|
"\tdbeq %1,1b\n"
|
|
#endif
|
|
"\tbne.b 1b\n" :
|
|
"=a" (cp), "=d" (n) :
|
|
"0" (cp), "1" (n) :
|
|
"cc");
|
|
return (cp - str) - 1;
|
|
}
|