ST STM32C0 Series Programming Manual

The STM32 Cortex-M4 instruction set PM0214
72/262 PM0214 Rev 9
The value to load or store can be a byte, halfword, word, or two words. Bytes and halfwords
can either be signed or unsigned (see Address alignment on page 65).
Table 26 shows the range of offsets for immediate, pre-indexed and post-indexed forms.
Restrictions
• For load instructions:
– Rt can be SP or PC for word loads only.
– Rt must be different from Rt2 for two-word loads.
– Rn must be different from Rt and Rt2 in the pre-indexed or post-indexed forms.
• When Rt is PC in a word load instruction.
– bit[0] of the loaded value must be 1 for correct execution.
– A branch occurs to the address created by changing bit[0] of the loaded value to 0.
– If the instruction is conditional, it must be the last instruction in the IT block.
• For store instructions:
– Rt can be SP for word stores only.
– Rt must not be PC.
– Rn must not be PC.
– Rn must be different from Rt and Rt2 in the pre-indexed or post-indexed forms
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.
Table 26. Immediate, pre-indexed and post-indexed offset ranges
Instruction type Immediate offset Pre-indexed Post-indexed
Word, halfword, signed
halfword, byte, or signed byte
-255 to 4095 -255 to 255 -255 to 255
Two words
Multiple of 4 in the
range -1020 to 1020
Multiple of 4 in the
range -1020 to 1020
Multiple of 4 in the
range -1020 to 1020

ST STM32C0 Series Specifications

General

Brand	ST
Model	STM32C0 Series
Category	Computer Hardware
Language	English