S3F84B8_UM_REV 1.00
6 INSTRUCTION SET
6-66
6.3.53 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 source into 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.