Outils pour utilisateurs
back2root:ibm-pc-ms-dos:instr:bsr
BSR - (386+ only)
BSR - Bit Scan Reverse (386+ only)
Scans source operand for first bit set. Sets ZF if a bit is found set and loads the destination with an index to first set bit. Clears ZF is no bits are found set. BSF scans forward across bit pattern (0-n) while BSR scans in reverse (n-0).
Usage:
BSR dest,src
Modifies flags:
ZF
| Clocks | Size | |||||
|---|---|---|---|---|---|---|
| Operands | 808x | 286 | 386 | 486 | Bytes | |
| reg,reg | - | - | 10+3n | 6-103 | 3 | |
| reg,mem | - | - | 10+3n | 7-104 | 3-7 | |
| reg32,reg32 | - | - | 10+3n | 6-103 | 3-7 | |
| reg32,mem32 | - | - | 10+3n | 7-104 | 3-7 | |
back2root/ibm-pc-ms-dos/instr/bsr.txt · Dernière modification : 2023/03/03 23:53 de 127.0.0.1
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