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Assembler User Guide

Preface Overview of the Assembler Overview of the ARM Architecture Structure of Assembly Language Modules Writing ARM Assembly Language Condition Codes Using the Assembler Symbols, Literals, Expressions, and Operators VFP Programming Assembler Command-line Options ARM and Thumb Instructions ARM and Thumb instruction summary Instruction width specifiers Flexible second operand (Operand2) Syntax of Operand2 as a constant Syntax of Operand2 as a register with optional shi Shift operations Saturating instructions Condition code suffixes ADC ADD ADR (PC-relative) ADR (register-relative) ADRL pseudo-instruction AND ASR B BFC BFI BIC BKPT BL BLX BX BXJ CBZ and CBNZ CDP and CDP2 CLREX CLZ CMP and CMN CPS CPY pseudo-instruction DBG DMB DSB EOR ERET HVC ISB IT LDC and LDC2 LDM LDR (immediate offset) LDR (PC-relative) LDR (register offset) LDR (register-relative) LDR pseudo-instruction LDR, unprivileged LDREX LSL LSR MCR and MCR2 MCRR and MCRR2 MLA MLS MOV MOV32 pseudo-instruction MOVT MRC and MRC2 MRRC and MRRC2 MRS (PSR to general-purpose register) MRS (system coprocessor register to ARM register) MSR (ARM register to system coprocessor register) MSR (general-purpose register to PSR) MUL MVN NEG pseudo-instruction NOP ORN (Thumb only) ORR PKHBT and PKHTB PLD and PLI POP PUSH QADD QADD8 QADD16 QASX QDADD QDSUB QSAX QSUB QSUB8 QSUB16 RBIT REV REV16 REVSH RFE ROR RRX RSB RSC SADD8 SADD16 SASX SBC SBFX SDIV SEL SETEND SEV SHADD8 SHADD16 SHASX SHSAX SHSUB8 SHSUB16 SMC SMLAxy SMLAD SMLAL SMLALD SMLALxy SMLAWy SMLSD SMLSLD SMMLA SMMLS SMMUL SMUAD SMULxy SMULL SMULWy SMUSD SRS SSAT SSAT16 SSAX SSUB8 SSUB16 STC and STC2 STM STR (immediate offset) STR (register offset) STR, unprivileged STREX SUB SUBS pc, lr SVC SWP and SWPB SXTAB SXTAB16 SXTAH SXTB SXTB16 SXTH SYS TBB and TBH TEQ TST UADD8 UADD16 UASX UBFX UDIV UHADD8 UHADD16 UHASX UHSAX UHSUB8 UHSUB16 UMAAL UMLAL UMULL UND pseudo-instruction UQADD8 UQADD16 UQASX UQSAX UQSUB8 UQSUB16 USAD8 USADA8 USAT USAT16 USAX USUB8 USUB16 UXTAB UXTAB16 UXTAH UXTB UXTB16 UXTH WFE WFI YIELD VFP Instructions Directives Reference Via File Syntax


10.125 SRS

Store Return State onto a stack.


SRS{addr_mode}{cond} sp{!}, #modenum
SRS{addr_mode}{cond} #modenum{!} ; This is pre-UAL syntax
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).
If addr_mode is omitted, it defaults to Increment After. You can also use stack oriented addressing mode suffixes, for example, when implementing stacks.
is an optional condition code.


cond is permitted only in Thumb code, using a preceding 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.


SRS stores the LR and the SPSR of the current mode, at the address contained in SP of the mode specified by modenum, and the following word respectively. Optionally updates SP of the mode specified by modenum. This is compatible with the normal use of the STM instruction for stack accesses.


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.
SRS is not permitted in a non-secure state if modenum specifies monitor mode.


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.


R13_usr  EQU     16
         SRSFD   sp,#R13_usr
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