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Volume 4: Base IA-32 Instruction Reference
AAS—ASCII Adjust AL After Subtraction
Description
Adjusts the result of the subtraction of two unpacked BCD values to create a unpacked
BCD result. The AL register is the implied source and destination operand for this
instruction. The AAS instruction is only useful when it follows a SUB instruction that
subtracts (binary subtraction) one unpacked BCD value from another and stores a byte
result in the AL register. The AAA instruction then adjusts the contents of the AL
register to contain the correct 1-digit unpacked BCD result.
If the subtraction produced a decimal carry, the AH register is decremented by 1, and
the CF and AF flags are set. If no decimal carry occurred, the CF and AF flags are
cleared, and the AH register is unchanged. In either case, the AL register is left with its
top nibble set to 0.
Operation
IF ((AL AND FH) > 9) OR (AF = 1)
THEN
AL
AL - 6;
AH
AH - 1;
AF
1;
CF
1;
ELSE
CF
0;
AF
0;
FI;
AL
AL AND FH;
Flags Affected
The AF and CF flags are set to 1 if there is a decimal borrow; otherwise, they are
cleared to 0. The OF, SF, ZF, and PF flags are undefined.
Additional Itanium System Environment Exceptions
Itanium Reg Faults NaT Register Consumption Abort.
Exceptions (All Operating Modes)
None.
Opcode
Instruction
Description
3F
AAS
ASCII adjust AL after subtraction
Содержание ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS VOLUME 3 REV 2.3
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Страница 11: ...x Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
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Страница 33: ...1 22 Volume 1 Part 1 Introduction to the Intel Itanium Architecture ...
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Страница 149: ...1 138 Volume 1 Part 2 About the Optimization Guide ...
Страница 191: ...1 180 Volume 1 Part 2 Predication Control Flow and Instruction Stream ...
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Страница 264: ...2 16 Volume 2 Part 1 Intel Itanium System Environment ...
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Страница 398: ...2 150 Volume 2 Part 1 Register Stack Engine ...
Страница 486: ...2 238 Volume 2 Part 1 IA 32 Interruption Vector Descriptions ...
Страница 749: ...2 501 Intel Itanium Architecture Software Developer s Manual Rev 2 3 Part II System Programmer s Guide ...
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Страница 754: ...2 506 Volume 2 Part 2 About the System Programmer s Guide ...
Страница 796: ...2 548 Volume 2 Part 2 Interruptions and Serialization ...
Страница 808: ...2 560 Volume 2 Part 2 Context Management ...
Страница 842: ...2 594 Volume 2 Part 2 Floating point System Software ...
Страница 850: ...2 602 Volume 2 Part 2 IA 32 Application Support ...
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Страница 1191: ...3 292 Volume 3 Pseudo Code Functions Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
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Страница 1494: ...4 192 Volume 4 Base IA 32 Instruction Reference FWAIT Wait See entry for WAIT ...
Страница 1564: ...4 262 Volume 4 Base IA 32 Instruction Reference LES Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1565: ...Volume 4 Base IA 32 Instruction Reference 4 263 LFS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1568: ...4 266 Volume 4 Base IA 32 Instruction Reference LGS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1583: ...Volume 4 Base IA 32 Instruction Reference 4 281 LSS Load Full Pointer See entry for LDS LES LFS LGS LSS ...
Страница 1647: ...Volume 4 Base IA 32 Instruction Reference 4 345 ROL ROR Rotate See entry for RCL RCR ROL ROR ...
Страница 1663: ...Volume 4 Base IA 32 Instruction Reference 4 361 SHL SHR Shift Instructions See entry for SAL SAR SHL SHR ...
Страница 1668: ...4 366 Volume 4 Base IA 32 Instruction Reference SIDT Store Interrupt Descriptor Table Register See entry for SGDT SIDT ...
Страница 1884: ...4 582 Volume 4 IA 32 SSE Instruction Reference ...
Страница 1885: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 Index ...
Страница 1886: ...Index Intel Itanium Architecture Software Developer s Manual Rev 2 3 ...
Страница 1898: ...INDEX Index 12 Index for Volumes 1 2 3 and 4 ...