Atmel SAM4S-XPLD Atmel ATSAM4S-XPLD ATSAM4S-XPLD Hoja De Datos

 101

SAM4S [DATASHEET]

11100E–ATARM–24-Jul-13

Push registers onto, and pop registers off a full-descending stack.

Syntax

PUSH{cond} reglist

POP{cond} reglist

where:

cond

reglist

is a non-empty list of registers, enclosed in braces. It can contain register
ranges. It must be comma separated if it contains more than one register or 
register range.

PUSH and POP are synonyms for STMDB and LDM (or LDMIA) with the memory addresses for the access based on SP,
and with the final address for the access written back to the SP. PUSH and POP are the preferred mnemonics in these
cases.

Operation

PUSH stores registers on the stack in order of decreasing the register numbers, with the highest numbered register using
the highest memory address and the lowest numbered register using the lowest memory address.

POP loads registers from the stack in order of increasing register numbers, with the lowest numbered register using the
lowest memory address and the highest numbered register using the highest memory address. 

See 

Restrictions

In these instructions:



reglist must not contain SP



For the PUSH instruction, reglist must not contain PC



For the POP instruction, reglist must not contain PC if it contains LR.

When PC is in reglist in a POP instruction:



Bit[0] of the value loaded to the PC must be 1 for correct execution, and a branch occurs to this halfword-aligned 
address



If the instruction is conditional, it must be the last instruction in the IT block.

Condition Flags

These instructions do not change the flags.

Examples

    PUSH    {R0,R4-R7}

    PUSH    {R2,LR}

    POP     {R0,R10,PC}