Samsung S3F80JB - Manual (Page 192)

INSTRUCTION SET S3F80JB
6-64
POPUD
— Pop User Stack (Decrementing)
POPUD dst,src
Operation: dst
← src
IR
← IR – 1
This instruction is used for user-defined stacks in the register file. The contents of the register file
location addressed by the user stack pointer are loaded into the destination. The user stack
pointer is then decremented.
Flags: No flags are affected.
Format:
Bytes Cycles Opcode
(Hex)
Addr Mode
dst src
opc src dst 3 8 92 R IR
Example: Given: Register 00H = 42H (user stack pointer register), register 42H = 6FH, and
register 02H = 70H:
POPUD 02H,@00H
→
Register 00H = 41H, register 02H = 6FH, register 42H = 6FH
If general register 00H contains the value 42H and register 42H the value 6FH, the statement
"POPUD 02H,@00H" loads the contents of register 42H into the destination register 02H. The
user stack pointer is then decremented by one, leaving the value 41H.