Pushud – Samsung S3F80JB User Manual

Page 195

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S3F80JB

INSTRUCTION SET

6-67

PUSHUD

Push User Stack (Decrementing)

PUSHUD

dst,src

Operation: IR

← IR – 1

dst

← src

This instruction is used to address user-defined stacks in the register file. PUSHUD decrements
the user stack pointer and loads the contents of the source into the register addressed by the
decremented stack pointer.

Flags:

No flags are affected.

Format:

Bytes Cycles Opcode

(Hex)

Addr Mode

dst src

opc dst src

3 8 82

IR

R

Example:

Given: Register 00H = 03H, register 01H = 05H, and register 02H = 1AH:

PUSHUD @00H,01H

Register 00H = 02H, register 01H = 05H, register 02H = 05H

If the user stack pointer (register 00H, for example) contains the value 03H, the statement
"PUSHUD @00H,01H" decrements the user stack pointer by one, leaving the value 02H. The
01H register value, 05H, is then loaded into the register addressed by the decremented user
stack pointer.

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