Samsung S3C84I8 User Manual page 190

INSTRUCTION SET
LDCD/LDED
dst,src
LDCD
dst,src
LDED
dst ← src
Operation:
rr ← rr – 1
These instructions are used for user stacks or block transfers of data from program or data
memory to the register file. The address of the memory location is specified by a working register
pair. The contents of the source location are loaded into the destination location. The memory
address is then decremented. The contents of the source are unaffected.
LDCD refers to program memory and LDED refers to external data memory. The assembler
makes "Irr" an even number for program memory and an odd number for data memory.
No flags are affected.
Flags:
Format:
opc
Given: R6 = 10H, R7 = 33H, R8 = 12H, program memory location 1033H = 0CDH, and
Examples:
external data memory location 1033H = 0DDH:
LDCD
LDED
LDED instruction can be used to read/write the data of 64-Kbyte data memory.
NOTE:
6-54
— Load Memory and Decrement
dst | src
R8,@RR6
R8,@RR6
Bytes Cycles
2
; 0CDH (contents of program memory location 1033H) is
loaded
; into R8 and RR6 is decremented by one;
; R8 = 0CDH, R6 = 10H, R7 = 32H (RR6 ← RR6 – 1)
; 0DDH (contents of data memory location 1033H) is
loaded
; into R8 and RR6 is decremented by one
(RR6 ← RR6 – 1);
; R8 = 0DDH, R6 = 10H, R7 = 32H
S3C84I8/F84I8/C84I9/F84I9
Opcode
(Hex)
10 E2
Addr Mode
dst src
r Irr