Samsung SC32442B54 User Manual page 142

SC32442B RISC MICROPROCESSOR
OPERATION
These instructions transfer byte or word values between registers and memory. Memory addresses are pre-
indexed using an offset register in the range 0-7. The THUMB assembler syntax is shown in Table 4-8.
L B THUMB assembler
0 0 STR Rd, [Rb, Ro]
0 1 STRB Rd, [Rb, Ro]
1 0 LDR Rd, [Rb, Ro]
1 1
LDRB Rd, [Rb, Ro]
INSTRUCTION CYCLE TIMES
All instructions in this format have an equivalent ARM instruction as shown in Table 4-8. The instruction cycle
times for the THUMB instruction are identical to that of the equivalent ARM instruction.
EXAMPLES
STR
LDRB
Table 4-8. Summary of Format 7 Instructions
ARM equivalent
STR Rd, [Rb, Ro]
STRB Rd, [Rb, Ro]
LDR Rd, [Rb, Ro]
LDRB Rd, [Rb, Ro]
R3, [R2,R6]
R2, [R0,R7]
Pre-indexed word store:
Calculate the target address by adding
together the value in Rb and the value in
Ro. Store the contents of Rd at the
address.
Pre-indexed byte store:
Calculate the target address by adding
together the value in Rb and the value in
Ro. Store the byte value in Rd at the
resulting address.
Pre-indexed word load:
Calculate the source address by adding
together the value in Rb and the value in
Ro. Load the contents of the address into
Rd.
Pre-indexed byte load:
Calculate the source address by adding
together the value in Rb and the value in
Ro. Load the byte value at the resulting
address.
; Store word in R3 at the address
formed by adding R6 to R2.
; Load into R2 the byte found at
the address formed by adding R7 to R0.
THUMB INSTRUCTION SET
Description
4-19