ARM instruction ldr and str analysis-EEWORLD

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The description of these two instructions on the S3C2440A datasheet is as follows:

SINGLE DATA TRANSFER (LDR, STR), The single data transfer instructions are used to load or store single bytes or words of data.

Simply put, it is a data transfer/storage instruction.

The following is the description of the two instruction formats on the datasheet:

{cond}{B}{T} Rd,

where:

LDR --- Load from memory into a register

STR --- Store from a register into memory

In the ARM architecture, data movement from memory to CPU can only be done through LDR/STR instructions. MOV can only move data between registers, or move immediate data to registers, and the length of the data cannot exceed 8 bits.

The following are specific application examples:

1. LDR r0,=label is used to load an immediate value or an address value into a specified register

1.1 If label is an immediate value: LDR r0,=0X123; store 0X123 in r0

1.2 If name is an identifier: LDR r0,=label_1; store the address pointed to by label_1 into r0

2. LDR r0,[r1] ; store the value in R1 into r0

3. LDR r1,[r2,#16] ; store the contents at address (r2+16) into r1

4. LDR r1,[r2],#4; store the content in address r2 into r1, and r2=r2+4

a. STR r1,[r2] ; Store the value in r1 to the address specified by r2

b. STR r1,[r2,#4] ; store the value in r1 to the address specified by r2+4

c. STR r1,[r2],#4; store the value in r1 to the address specified by r2, and r2=r2+4

Keywords：ldr str Reference address：ARM instruction ldr and str analysis

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