Store Return State onto a stack.
SRS{addr_mode
}{cond
} sp{!}, #modenum
SRS{addr_mode
}{cond
} #modenum
{!} ; This is a pre-UAL syntax
where:
-
is any one of the following:
-
Increment address After each transfer
-
Increment address Before each transfer (ARM only)
-
Decrement address After each transfer (ARM only)
-
Decrement address Before each transfer (Full Descending stack).
IA
IB
DA
DB
If
is omitted, it defaults to Increment After. You can also use stack oriented addressing mode suffixes, for example, when implementing stacks.addr_mode
-
-
is an optional condition code.
Note
is permitted only in Thumb code, using a precedingcond
IT
instruction. This is an unconditional instruction in ARM. -
is an optional suffix. If
!
is present, the final address is written back into the SP of the mode specified by
.modenum
-
specifies the number of the mode whose banked SP is used as the base register. You must use only the defined mode numbers.
addr_mode
cond
!
modenum
SRS
stores the LR and the SPSR of the current mode, at the address contained in SP of the mode specified by
, and the following word respectively. Optionally updates SP of the mode specified by modenum
. This is compatible with the normal use of the modenum
STM
instruction for stack accesses.
Note
For full descending stack, you must use SRSFD
or SRSDB
.
You can use SRS
to store return state for an exception handler on a different stack from the one automatically selected.
Where addresses are not word-aligned, SRS
ignores the least significant two bits of the specified address.
The time order of the accesses to individual words of memory generated by SRS
is not architecturally defined. Do not use this instruction on memory-mapped I/O locations where access order matters.
Do not use SRS
in User and System modes because these modes do not have a SPSR.
Do not use SRS
in Thumb-2EE.
SRS
is not permitted in a non-secure state if
specifies monitor mode.modenum
This ARM instruction is available in ARMv6 and above.
This 32-bit Thumb instruction is available in ARMv6T2 and above, except the ARMv7-M architecture.
There is no 16-bit version of this instruction.
-
Concepts
- Reference: