INSTRUCTION SET DESCRIPTIONS
C-38
RET
Return:
RET
optional-pop-value
Transfers control from a procedure
back to the instruction following the
CALL that activated the procedure.
The assembler generates an intra-
segment RET if the programmer has
defined the procedure near, or an
intersegment RET if the procedure has
been defined as far. RET pops the
word at the top of the stack (pointed to
by register SP) into the instruction
pointer and increments SP by two. If
RET is intersegment, the word at the
new top of stack is popped into the CS
register, and SP is again incremented
by two. If an optional pop value has
been specified, RET adds that value to
SP.
Instruction Operands:
RET immed8
(IP)
←
((SP) = 1:(SP))
(SP)
←
(SP) + 2
if
inter-segment
then
(CS)
←
((SP) + 1:(SP))
(SP)
←
(SP) + 2
if
add immed8 to SP
then
(SP)
←
(SP) + data
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
ROL
Rotate Left:
ROL dest, count
Rotates the destination byte or word
left by the number of bits specified in
the count operand.
Instruction Operands:
ROL reg, n
ROL mem, n
ROL reg, CL
ROL mem CL
(temp)
←
count
do while (temp)
≠
0
(CF)
←
high-order bit of (dest)
(dest)
←
(dest) × 2 + (CF)
(temp)
←
(temp) – 1
if
count = 1
then
if
high-order bit of (dest)
≠
(CF)
then
(OF)
←
1
else
(OF)
←
0
else
(OF) undefined
AF –
CF
ü
DF –
IF –
OF
ü
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 80C186XL
Страница 1: ...80C186XL 80C188XL Microprocessor User s Manual...
Страница 2: ...80C186XL 80C188XL Microprocessor User s Manual 1995...
Страница 18: ...1 Introduction...
Страница 19: ......
Страница 27: ......
Страница 28: ...2 Overview of the 80C186 Family Architecture...
Страница 29: ......
Страница 79: ......
Страница 80: ...3 Bus Interface Unit...
Страница 81: ......
Страница 127: ......
Страница 128: ...4 Peripheral Control Block...
Страница 129: ......
Страница 137: ......
Страница 138: ...5 ClockGenerationand Power Management...
Страница 139: ......
Страница 154: ...6 Chip Select Unit...
Страница 155: ......
Страница 178: ...7 Refresh Control Unit...
Страница 179: ......
Страница 193: ......
Страница 194: ...8 Interrupt Control Unit...
Страница 195: ......
Страница 227: ......
Страница 228: ...9 Timer Counter Unit...
Страница 229: ......
Страница 253: ......
Страница 254: ...10 Direct Memory Access Unit...
Страница 255: ......
Страница 283: ......
Страница 284: ...11 Math Coprocessing...
Страница 285: ......
Страница 302: ...12 ONCE Mode...
Страница 303: ......
Страница 306: ...A 80C186 Instruction Set Additions and Extensions...
Страница 307: ......
Страница 318: ...B Input Synchronization...
Страница 319: ......
Страница 322: ...C Instruction Set Descriptions...
Страница 323: ......
Страница 371: ......
Страница 372: ...D Instruction Set Opcodes and Clock Cycles...
Страница 373: ......
Страница 396: ...Index...
Страница 397: ......