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Volume 4: Base IA-32 Instruction Reference
4:37
BSR—Bit Scan Reverse
Description
Searches the source operand (second operand) for the most significant set bit (1 bit). If
a most significant 1 bit is found, its bit index is stored in the destination operand (first
operand). The source operand can be a register or a memory location; the destination
operand is a register. The bit index is an unsigned offset from bit 0 of the source
operand. If the contents source operand are 0, the contents of the destination operand
is undefined.
Operation
IF SRC = 0
THEN
ZF
1;
DEST is undefined;
ELSE
ZF
0;
temp
OperandSize - 1;
WHILE Bit(SRC, temp) = 0
DO
temp
temp
1;
DEST
temp;
OD;
FI;
Flags Affected
The ZF flag is set to 1 if all the source operand is 0; otherwise, the ZF flag is cleared.
The CF, OF, SF, AF, and PF, flags are undefined.
Additional Itanium System Environment Exceptions
Itanium Reg Faults NaT Register Consumption Abort.
Itanium Mem FaultsVHPT Data Fault, Nested TLB Fault, Data TLB Fault, Alternate Data
TLB Fault, Data Page Not Present Fault, Data NaT Page Consumption
Abort, Data Key Miss Fault, Data Key Permission Fault, Data Access
Rights Fault, Data Access Bit Fault, Data Dirty Bit Fault
Opcode
Instruction
Description
0F BD
BSR
r16,r/m16
Bit scan reverse on
r/m16
0F BD
BSR
r32,r/m32
Bit scan reverse on
r/m32
Summary of Contents for ITANIUM ARCHITECTURE
Page 1: ......
Page 7: ...402 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 199: ...4 192 Volume 4 Base IA 32 Instruction Reference FWAIT Wait See entry for WAIT ...
Page 352: ...Volume 4 Base IA 32 Instruction Reference 4 345 ROL ROR Rotate See entry for RCL RCR ROL ROR ...
Page 589: ...4 582 Volume 4 IA 32 SSE Instruction Reference ...
Page 590: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index ...
Page 591: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Page 603: ...INDEX Index 12 Index for Volumes 1 2 3 and 4 ...
Page 604: ......