Atmel SAM4S Series, Preliminary Data Sheet

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11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
Condition Flags
These instructions do not change the flags.
Examples
LDR R8, [R10] ; Loads R8 from the address in R10.
LDRNE R2, [R5, #960]! ; Loads (conditionally) R2 from a word
; 960 bytes above the address in R5, and
; increments R5 by 960.
STR R2, [R9,#const-struc] ; const-struc is an expression evaluating
; to a constant in the range 0-4095.
STRH R3, [R4], #4 ; Store R3 as halfword data into address in
; R4, then increment R4 by 4
LDRD R8, R9, [R3, #0x20] ; Load R8 from a word 32 bytes above the
; address in R3, and load R9 from a word 36
; bytes above the address in R3
STRD R0, R1, [R8], #-16 ; Store R0 to address in R8, and store R1 to
; a word 4 bytes above the address in R8,
; and then decrement R8 by 16.
11.6.4.3 LDR and STR, Register Offset
Load and Store with register offset.
Syntax
op{type}{cond} Rt, [Rn, Rm {, LSL #n}]
where:
op is one of:
LDR Load Register.
STR Store Register.
type is one of:
B unsigned byte, zero extend to 32 bits on loads.
SB signed byte, sign extend to 32 bits (LDR only).
H unsigned halfword, zero extend to 32 bits on loads.
SH signed halfword, sign extend to 32 bits (LDR only).
- omit, for word.
cond is an optional condition code, see “Conditional Execution” .
Rt is the register to load or store.
Rn is the register on which the memory address is based.
Rm is a register containing a value to be used as the offset.
LSL #n is an optional shift, with n in the range 0 to 3.
Operation
LDR instructions load a register with a value from memory.
STR instructions store a register value into memory.