Motorola DSP56800 Manual page 376

POP
Operation:
X:(SP) →
D
SP-1 →
SP
Description: Read one location from the software stack into a destination register (D) and post-decrement the SP.
Implementation Note:
This instruction is implemented by the assembler using either a MOVE or LEA instruction, depending
on the form. When a destination register is specified, a MOVE (SP)-,<register> instruction is
assembled. When no destination register is specified, POP assembles as LEA (SP)- . The instruction
will always disassemble as either MOVE or LEA.
Example:
POP
Before Execution
X:$0100
Explanation of Example:
Prior to execution, the LC register contains the value $0099, and the SP contains the value $0100. The
POP instruction reads from the location in X data memory pointed to by the SP and places this value
in the LC register. The SP is then decremented after the read from memory.
Condition Codes Affected:
The condition codes are not affected by this instruction.
Instruction Fields:
Operation
POP
Timing: 2 oscillator clock cycles
Memory:
1 program word
A-146
Pop from Stack
Assembler Syntax:
POP
LC
AAAA
LC
0099
SP
0100
Operands C
Any register 2
(No register 2
specified)
DSP56800 Family Manual
D
After Execution
X:$0100
LC
SP
W
1 Pop a single stack location
1 Simply decrements the SP
POP
AAAA
AAAA
00FF
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