C-43
INSTRUCTION SET DESCRIPTIONS
SHR
Shift Logical Right:
SHR
dest, src
Shifts the bits in the destination
operand (byte or word) to the right by
the number of bits specified in the
count operand. Zeros are shifted in on
the left. If the sign bit retains its original
value, then OF is cleared.
Instruction Operands:
SHR reg, n
SHR mem, n
SHR reg, CL
SHR mem, CL
(temp)
←
count
do while (temp)
≠
0
(CF)
←
low-order bit of (dest)
(dest)
←
(dest) / 2
(temp)
←
(temp) – 1
if
count = 1
then
if
high-order bit of (dest)
≠
next-to-high-order bit of (dest)
then
(OF)
←
1
else
(OF)
←
0
else
(OF) undefined
AF ?
CF
ü
DF –
IF –
OF
ü
PF
ü
SF
ü
TF –
ZF
ü
STC
Set Carry Flag:
STC
Sets CF to 1.
Instruction Operands:
none
(CF)
←
1
AF –
CF
ü
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
STD
Set Direction Flag:
STD
Sets DF to 1 causing the string instruc-
tions to auto-decrement the SI and/or
DI index registers.
Instruction Operands:
none
(DF)
←
1
AF –
CF –
DF
ü
IF –
OF –
PF –
SF –
TF –
ZF –
Table C-4. Instruction Set (Continued)
Name
Description
Operation
Flags
Affected
NOTE: The three symbols used in the Flags Affected column are defined as follows:
– the contents of the flag remain unchanged after the instruction is executed
? the contents of the flag is undefined after the instruction is executed
ü
the flag is updated after the instruction is executed
Содержание 80C186EA
Страница 1: ...80C186EA 80C188EA Microprocessor User s Manual...
Страница 2: ...80C186EA 80C188EA Microprocessor User s Manual 1995...
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Страница 20: ...1 Introduction...
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Страница 28: ...2 Overview of the 80C186 Family Architecture...
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Страница 80: ...3 Bus Interface Unit...
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Страница 130: ...4 Peripheral Control Block...
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Страница 140: ...5 ClockGenerationand Power Management...
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Страница 166: ...6 Chip Select Unit...
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Страница 190: ...7 Refresh Control Unit...
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Страница 206: ...8 Interrupt Control Unit...
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Страница 239: ...INTERRUPT CONTROL UNIT 8 32...
Страница 240: ...9 Timer Counter Unit...
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Страница 266: ...10 Direct Memory Access Unit...
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Страница 295: ...DIRECT MEMORY ACCESS UNIT 10 28...
Страница 296: ...11 Math Coprocessing...
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Страница 314: ...12 ONCE Mode...
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Страница 318: ...A 80C186 Instruction Set Additions and Extensions...
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Страница 330: ...B Input Synchronization...
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Страница 334: ...C Instruction Set Descriptions...
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Страница 383: ...INSTRUCTION SET DESCRIPTIONS C 48...
Страница 384: ...D Instruction Set Opcodes and Clock Cycles...
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Страница 408: ...Index...
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