Ldcpd/Ldepd — Load Memory With Pre-Decrement - Samsung S3F84B8 User Manual

S3F84B8_UM_REV 1.00
6.3.42 LDCPD/LDEPD — LOAD MEMORY WITH PRE-DECREMENT
LDCPD/
dst,src
LDEPD
rr  rr – 1
Operation:
dst  src
These instructions are used for block transfers of data from program or data memory from the
register file. The address of memory location is specified by a working register pair and is first
decremented. After this step, the contents of source location are loaded into destination location.
The contents of source remain unaffected.
LDCPD refers to program memory and LDEPD refers to external data memory. The assembler
makes 'Irr' an even number for program memory and an odd number for external data memory.
No flags are affected.
Flags:
Format:
opc
Given R0 = 77H, R6 = 30H, and R7 = 00H:
Examples:
LDCPD @RR6,R0
LDEPD @RR6,R0
src | dst
; (RR6  RR6 – 1)
; 77H (contents of R0) is loaded into program memory location
; 2FFFH (3000H – 1H)
; R0 = 77H, R6 = 2FH, R7 = 0FFH
; (RR6  RR6 – 1)
; 77H (contents of R0) is loaded into external data memory
; location 2FFFH (3000H – 1H)
; R0 = 77H, R6 = 2FH, R7 = 0FFH
Bytes Cycles
2
6-55
6 INSTRUCTION SET
Opcode Addr Mode
(Hex) dst
14 F2
src
Irr r