UM10462 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2016. All rights reserved.
User manual Rev. 5.5 — 21 December 2016 465 of 523
NXP Semiconductors
UM10462
Chapter 24: LPC11U3x/2x/1x Appendix ARM Cortex-M0
24.4.4.5.1 Syntax
LDM Rn{!}, reglist
STM Rn!, reglist
where:
Rn is the register on which the memory addresses are based.
! writeback suffix.
reglist is a list of one or more registers to be loaded or stored, enclosed in braces. It can
contain register ranges. It must be comma separated if it contains more than one
register or register range, see Section 24–24.4.4.5.5
.
LDMIA and LDMFD are synonyms for LDM. LDMIA refers to the base register being
Incremented After each access. LDMFD refers to its use for popping data from Full
Descending stacks.
STMIA and STMEA are synonyms for STM. STMIA refers to the base register being
Incremented After each access. STMEA refers to its use for pushing data onto Empty
Ascending stacks.
24.4.4.5.2 Operation
LDM instructions load the registers in reglist with word values from memory addresses
based on Rn.
STM instructions store the word values in the registers in reglist to memory addresses
based on Rn.
The memory addresses used for the accesses are at 4-byte intervals ranging from the
value in the register specified by Rn to the value in the register specified by Rn + 4 * (n-1),
where n is the number of registers in reglist. The accesses happens in order of increasing
register numbers, with the lowest numbered register using the lowest memory address
and the highest number register using the highest memory address. If the writeback suffix
is specified, the value in the register specified by Rn + 4 *n is written back to the register
specified by Rn.
24.4.4.5.3 Restrictions
In these instructions:
• reglist and Rn are limited to R0-R7.
• the writeback suffix must always be used unless the instruction is an LDM where
reglist also contains Rn, in which case the writeback suffix must not be used.
• the value in the register specified by Rn must be word aligned. See
Section 24–24.4.3.4
for more information.
• for STM, if Rn appears in reglist, then it must be the first register in the list.
24.4.4.5.4 Condition flags
These instructions do not change the flags.
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