| ??? 08/13/07 19:40 Modified: 08/13/07 19:41 Read: times |
#143224 - now it\'s my pencil time... Responding to: ???'s previous message |
... to sit down and figure out how THIS ONE works...
:-) Thanks, Dan. JW PS I tried SDCC just to have a complete picture: 35 cycles (nothing spectacular...)
void CRCNib(unsigned char b)
131 ; crc.c:5: CRCLo ^= b;
0005 E5 82 134 mov a,dpl
0007 FA 135 mov r2,a
0008 62*00 136 xrl _CRCLo,a
137 ; crc.c:6: b = CRCHi;
000A AA*01 139 mov r2,_CRCHi
140 ; crc.c:7: CRCHi = CRCLo ^ (CRCLo << 4);
000C E5*00 144 mov a,_CRCLo
000E C4 145 swap a
000F 54 F0 146 anl a,#0xf0
0011 FB 148 mov r3,a
0012 65*00 150 xrl a,_CRCLo
151 ; crc.c:8: CRCLo = b;
153 ; crc.c:9: CRCLo ^= (b = CRCHi >> 4);
0014 F5*01 157 mov _CRCHi,a
0016 8A*00 158 mov _CRCLo,r2
0018 C4 160 swap a
0019 54 0F 161 anl a,#0x0f
001B FB 164 mov r3,a
001C 8B 02 165 mov ar2,r3
001E 62*00 167 xrl _CRCLo,a
168 ; crc.c:10: b = CRCHi ^ (b >> 1);
0020 EA 172 mov a,r2
0021 C3 173 clr c
0022 13 174 rrc a
0023 FB 176 mov r3,a
0024 65*01 178 xrl a,_CRCHi
0026 FA 179 mov r2,a
180 ; crc.c:11: CRCLo ^= CRCHi << 3;
0027 E5*01 184 mov a,_CRCHi
0029 C4 185 swap a
002A 03 186 rr a
002B 54 F8 187 anl a,#0xf8
002D FB 189 mov r3,a
002E 62*00 191 xrl _CRCLo,a
192 ; crc.c:12: CRCHi = b;
0030 8A*01 194 mov _CRCHi,r2
0032 22 196 ret
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