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THUMB INSTRUCTION SET S3C2410A
4-26
FORMAT 11: SP-RELATIVE LOAD/STORE
[7:0] Immediate Value
[10:8] Destination Register
[11] Load/Store Bit
0 = Store to memory
1 = Load from memory
15 0
1
14
10
0 0
13 12
11
Word 81 L Rd
78
Figure 4-12. Format 11
OPERATION
The instructions in this group perform an SP-relative load or store. The THUMB assembler syntax is shown in the
following table.
Table 4-12. SP-Relative Load/Store Instructions
L THUMB assembler ARM equivalent Action
0 STR Rd, [SP, #Imm] STR Rd, [R13 #Imm] Add unsigned offset (255 words, 1020 bytes)
in Imm to the current value of the SP (R7).
Store the contents of Rd at the resulting
address.
1 LDR Rd, [SP, #Imm] LDR Rd, [R13 #Imm] Add unsigned offset (255 words, 1020 bytes)
in Imm to the current value of the SP (R7).
Load the word from the resulting address into
Rd.
NOTE: The offset supplied in #Imm is a full 10-bit address, but must always be word-aligned (ie bits 1:0 set to 0),
since the assembler places #Imm >> 2 in the Word8 field.