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C-35
INSTRUCTION SET DESCRIPTIONS
PUSHA Push All:
PUSHA
Pushes all data, pointer, and index
registers onto the stack . The order in
which the registers are saved is: AX,
CX, DX, BX, SP, BP, SI, and DI. The
SP value pushed is the SP value
before the first register (AX) is pushed.
Instruction Operands:
none
temp ← (SP)
(SP) ← (SP) – 2
((SP) + 1:(SP)) ← (AX)
(SP) ← (SP) – 2
((SP) + 1:(SP)) ← (CX)
(SP) ← (SP) – 2
((SP) + 1:(SP)) ← (DX)
(SP) ← (SP) – 2
((SP) + 1:(SP)) ← (BX)
(SP) ← (SP) – 2
((SP) + 1:(SP)) ← (temp)
(SP) ← (SP) – 2
((SP) + 1:(SP)) ← (BP)
(SP) ← (SP) – 2
((SP) + 1:(SP)) ← (SI)
(SP) ← (SP) – 2
((SP) + 1:(SP)) ← (DI)
AF –
CF –
DF –
IF –
OF –
PF –
SF –
TF –
ZF –
PUSHF Push Flags:
PUSHF
Decrements SP by two and then
transfers all flags to the word at the top
of stack pointed to by SP.
Instruction Operands:
none
(SP) ← (SP) – 2
((SP) + 1:(SP)) ← Flags
AF –
CF –
DF –
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
the flag is updated after the instruction is executed