131 lines
4.5 KiB
C
131 lines
4.5 KiB
C
|
/*****************************************************************************/
|
|||
|
|
/* */
|
|||
|
|
/* shift.c */
|
|||
|
|
/* */
|
|||
|
|
/* Safe shift routines */
|
|||
|
|
/* */
|
|||
|
|
/* */
|
|||
|
|
/* */
|
|||
|
|
/* (C) 2003 Ullrich von Bassewitz */
|
|||
|
|
/* R<>merstra<72>e 52 */
|
|||
|
|
/* D-70794 Filderstadt */
|
|||
|
|
/* EMail: uz@cc65.org */
|
|||
|
|
/* */
|
|||
|
|
/* */
|
|||
|
|
/* This software is provided 'as-is', without any expressed or implied */
|
|||
|
|
/* warranty. In no event will the authors be held liable for any damages */
|
|||
|
|
/* arising from the use of this software. */
|
|||
|
|
/* */
|
|||
|
|
/* Permission is granted to anyone to use this software for any purpose, */
|
|||
|
|
/* including commercial applications, and to alter it and redistribute it */
|
|||
|
|
/* freely, subject to the following restrictions: */
|
|||
|
|
/* */
|
|||
|
|
/* 1. The origin of this software must not be misrepresented; you must not */
|
|||
|
|
/* claim that you wrote the original software. If you use this software */
|
|||
|
|
/* in a product, an acknowledgment in the product documentation would be */
|
|||
|
|
/* appreciated but is not required. */
|
|||
|
|
/* 2. Altered source versions must be plainly marked as such, and must not */
|
|||
|
|
/* be misrepresented as being the original software. */
|
|||
|
|
/* 3. This notice may not be removed or altered from any source */
|
|||
|
|
/* distribution. */
|
|||
|
|
/* */
|
|||
|
|
/*****************************************************************************/
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
/* According to the C standard, shifting a data type by the number of bits it
|
|||
|
|
* has causes undefined behaviour. So
|
|||
|
|
*
|
|||
|
|
* unsigned long l = 1;
|
|||
|
|
* unsigned u =32;
|
|||
|
|
* l <<= u;
|
|||
|
|
*
|
|||
|
|
* maybe illegal. The functions in this module behave safely in this respect,
|
|||
|
|
* and they use proper casting to distinguish signed from unsigned shifts.
|
|||
|
|
* They are not a general purpose replacement for the shift operator!
|
|||
|
|
*/
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
#include <limits.h>
|
|||
|
|
|
|||
|
|
/* common */
|
|||
|
|
#include "shift.h"
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
/*****************************************************************************/
|
|||
|
|
/* Code */
|
|||
|
|
/*****************************************************************************/
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
long asl_l (long l, unsigned count)
|
|||
|
|
/* Arithmetic shift left l by count. */
|
|||
|
|
{
|
|||
|
|
while (1) {
|
|||
|
|
if (count >= CHAR_BIT * sizeof (l)) {
|
|||
|
|
l <<= (CHAR_BIT * sizeof (l) - 1);
|
|||
|
|
count -= (CHAR_BIT * sizeof (l) - 1);
|
|||
|
|
} else {
|
|||
|
|
l <<= count;
|
|||
|
|
break;
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
return l;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
long asr_l (long l, unsigned count)
|
|||
|
|
/* Arithmetic shift right l by count */
|
|||
|
|
{
|
|||
|
|
while (1) {
|
|||
|
|
if (count >= CHAR_BIT * sizeof (l)) {
|
|||
|
|
l >>= (CHAR_BIT * sizeof (l) - 1);
|
|||
|
|
count -= (CHAR_BIT * sizeof (l) - 1);
|
|||
|
|
} else {
|
|||
|
|
l >>= count;
|
|||
|
|
break;
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
return l;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
unsigned long shl_l (unsigned long l, unsigned count)
|
|||
|
|
/* Logical shift left l by count */
|
|||
|
|
{
|
|||
|
|
while (1) {
|
|||
|
|
if (count >= CHAR_BIT * sizeof (l)) {
|
|||
|
|
l <<= (CHAR_BIT * sizeof (l) - 1);
|
|||
|
|
count -= (CHAR_BIT * sizeof (l) - 1);
|
|||
|
|
} else {
|
|||
|
|
l <<= count;
|
|||
|
|
break;
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
return l;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
|
|||
|
|
|
|||
|
|
unsigned long shr_l (unsigned long l, unsigned count)
|
|||
|
|
/* Logical shift right l by count */
|
|||
|
|
{
|
|||
|
|
while (1) {
|
|||
|
|
if (count >= CHAR_BIT * sizeof (l)) {
|
|||
|
|
l >>= (CHAR_BIT * sizeof (l) - 1);
|
|||
|
|
count -= (CHAR_BIT * sizeof (l) - 1);
|
|||
|
|
} else {
|
|||
|
|
l >>= count;
|
|||
|
|
break;
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
return l;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
|
|||
|
|
|