| ??? 04/02/08 17:06 Read: times |
#152896 - use a C-compiler and r = (r15); Responding to: ???'s previous message |
Let a C-compiler (using sdcc here) do the work for you:
unsigned int r;
void f()
{
r = (r<<1) | (r>>15);
}
void g()
{
r = (r<<15) | (r>>1);
}
generates this code with "sdcc -c rotate16.c":
0000 101 _f:
110 ; rotate16.c:5: r = (r<<1) | (r>>15);
0000 E5*00 111 mov a,_r
0002 33 112 rlc a
0003 C5*01 113 xch a,(_r + 1)
0005 33 114 rlc a
0006 C5*01 115 xch a,(_r + 1)
0008 92 E0 116 mov acc.0,c
000A F5*00 117 mov _r,a
000C 22 118 ret
119 ;-------------------------------------
000D 127 _g:
128 ; rotate16.c:10: r = (r<<15) | (r>>1);
000D E5*01 129 mov a,(_r + 1)
000F 13 130 rrc a
0010 C5*00 131 xch a,_r
0012 13 132 rrc a
0013 C5*00 133 xch a,_r
0015 92 E7 134 mov acc.7,c
0017 F5*01 135 mov (_r + 1),a
0019 22 136 ret
|
| Topic | Author | Date |
| rotating a sixteen bit value | 01/01/70 00:00 | |
| have you read about the entire instruction set? | 01/01/70 00:00 | |
| Q: How can you eat a whole whale? | 01/01/70 00:00 | |
use a C-compiler and r = (r<<1) | (r>>15); | 01/01/70 00:00 |