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Volume 4: Base IA-32 Instruction Reference
BTR—Bit Test and Reset
Description
Selects the bit in a bit string (specified with the first operand, called the bit base) at the
bit-position designated by the bit offset operand (second operand), stores the value of
the bit in the CF flag, and clears the selected bit in the bit string to 0. The bit base
operand can be a register or a memory location; the bit offset operand can be a register
or an immediate value. If the bit base operand specifies a register, the instruction takes
the modulo 16 or 32 (depending on the register size) of the bit offset operand, allowing
any bit position to be selected in a 16- or 32-bit register, respectively. If the bit base
operand specifies a memory location, it represents the address of the byte in memory
that contains the bit base (bit 0 of the specified byte) of the bit string. The offset
operand then selects a bit position within the range
2
31
to 2
31
1 for a register offset
and 0 to 31 for an immediate offset.
Some assemblers support immediate bit offsets larger than 31 by using the immediate
bit offset field in combination with the displacement field of the memory operand. See
for more information on this addressing mechanism.
Operation
CF
Bit(BitBase, BitOffset)
Bit(BitBase, BitOffset)
0;
Flags Affected
The CF flag contains the value of the selected bit before it is cleared. The OF, SF, ZF, 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 B3
BTR
r/m16,r16
Store selected bit in CF flag and clear
0F B3
BTR
r/m32,r32
Store selected bit in CF flag and clear
0F BA /6
ib
BTR
r/m16,imm8
Store selected bit in CF flag and clear
0F BA /6
ib
BTR
r/m32,imm8
Store selected bit in CF flag and clear
Содержание ITANIUM ARCHITECTURE
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Страница 7: ...402 Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 199: ...4 192 Volume 4 Base IA 32 Instruction Reference FWAIT Wait See entry for WAIT ...
Страница 269: ...4 262 Volume 4 Base IA 32 Instruction Reference LES Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 270: ...Volume 4 Base IA 32 Instruction Reference 4 263 LFS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 273: ...4 266 Volume 4 Base IA 32 Instruction Reference LGS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 288: ...Volume 4 Base IA 32 Instruction Reference 4 281 LSS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 352: ...Volume 4 Base IA 32 Instruction Reference 4 345 ROL ROR Rotate See entry for RCL RCR ROL ROR ...
Страница 368: ...Volume 4 Base IA 32 Instruction Reference 4 361 SHL SHR Shift Instructions See entry for SAL SAR SHL SHR ...
Страница 373: ...4 366 Volume 4 Base IA 32 Instruction Reference SIDT Store Interrupt Descriptor Table Register See entry for SGDT SIDT ...
Страница 589: ...4 582 Volume 4 IA 32 SSE Instruction Reference ...
Страница 590: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index ...
Страница 591: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 603: ...INDEX Index 12 Index for Volumes 1 2 3 and 4 ...
Страница 604: ......