push

Push (Thumb)

PUSH <registers>

Push registers to stack (Thumb 16-bit).

Pseudocode Operation

address ← SP
for each register in register_list (in descending order):
  address ← address - 4
  [address] ← register
SP ← address
if M == 1 then
  address ← address - 4
  [address] ← LR
  SP ← address

Example

PUSH registers

Encoding

Binary Layout

1011

15:12

0

11

10

10:9

M

8

register_list

7:0

 

Format Thumb Store Multiple

Opcode 0xB400

Extension T32 (Base)

Operands

• registers
  List

Related

Other forms of push

• push Push Multiple Registers (A32)

More in T32 (Base)

Reference

View in Arm A64 ISA Reference ↗ Arm AArch32 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0xB400	PUSH{<c>}{<q>} <registers>		T32		1011 | 0 | 10 | M | register_list
0x092D0000	PUSH{<c>}{<q>} <registers>		A32		cond | 100 | 1 | 0 | 0 | 1 | 0 | 1101 | register_list
0xE92D0000	PUSH{<c>}.W <registers>		T32		1110100 | 10 | 0 | 1 | 0 | 1101 | 0 | M | register_list
0x052D0004	PUSH{<c>}{<q>} <single_register_list>		A32		cond | 010 | 1 | 0 | 0 | 1 | 0 | 1101 | Rt | 000000000100
0xF84D0D04	PUSH{<c>}{<q>} <single_register_list>		T32		111110000 | 10 | 0 | 1101 | Rt | 1 | 1 | 0 | 1 | 00000100

Description

Push Multiple Registers to Stack stores multiple general-purpose registers to the stack, storing to consecutive memory locations ending just below the address in SP, and updates SP to point to the start of the stored data. The lowest-numbered register is stored to the lowest memory address, through to the highest-numbered register to the highest memory address. See also Encoding of lists of general-purpose registers and the PC.

Operation

if ConditionPassed() then
    EncodingSpecificOperations();
    address = R[13] - 4*BitCount(registers);
    for i = 0 to 14
        if registers<i> == '1' then
            if i == 13 && i != LowestSetBit(registers) then  // Only possible for encoding A1
                MemA[address,4] = bits(32) UNKNOWN;
            else
                if UnalignedAllowed then
                    MemU[address,4] = R[i];
                else
                    MemA[address,4] = R[i];
            address = address + 4;
    if registers<15> == '1' then  // Only possible for encoding A1 or A2
        if UnalignedAllowed then
            MemU[address,4] = PCStoreValue();
        else
            MemA[address,4] = PCStoreValue();
    R[13] = R[13] - 4*BitCount(registers);