Computer Laboratory

Raspberry Pi

ARM Reference

This page contains a reference for the ARMv6 instruction set, register set, and also the GNU Assembler program syntax.

1 Tutorial ARM Instructions

The following is a list of all the instruction boxes in the courses in order.

ldr reg,=val puts the number val into the register named reg.

mov reg,#val puts the number val into the register named reg.

lsl reg,#val shifts the binary representation of the number in reg by val places to the left.

str reg,[dest,#val] stores the number in reg at the address given by dest + val.

name: labels the next line name.

b label causes the next line to be executed to be label.

sub reg,#val subtracts the number val from the value in reg.

cmp reg,#val compares the value in reg with the number val.

Suffix ne causes the command to be executed only if the last comparison determined that the numbers were not equal.

.globl lbl makes the label lbl accessible from other files.

mov reg1,reg2 copies the value in reg2 into reg1.

Suffix ls causes the command to be executed only if the last comparison determined that the first number was less than or the same as the second. Unsigned.

Suffix hi causes the command to be executed only if the last comparison determined that the first number was higher than the second. Unsigned.

push {reg1,reg2,...} copies the registers in the list reg1,reg2,... onto the top of the stack. Only general purpose registers and lr can be pushed.

bl lbl sets lr to the address of the next instruction and then branches to the label lbl.

add reg,#val adds the number val to the contents of the register reg.

Argument shift reg,lsl #val shifts the binary representation of the number in reg left by val before using it in the operation before.

lsl reg,amt shifts the binary representation of the number in reg left by the number in amt.

str reg,[dst] is the same as str reg,[dst,#0].

pop {reg1,reg2,...} copies the values from the top of the stack into the register list reg1,reg2,.... Only general purpose registers and pc can be popped.

alias .req reg sets alias to mean the register reg.

.unreq alias removes the alias alias.

lsr dst,src,#val shifts the binary representation of the number in src right by val, but stores the result in dst.

and reg,#val computes the Boolean and function of the number in reg with val.

teq reg,#val checks if the number in reg is equal to val.

ldrd regLow,regHigh,[src,#val] loads 8 bytes from the address given by the number in src plus val into regLow and regHigh.

.align num ensures the address of the next line is a multiple of 2num.

.int val outputs the number val.

tst reg,#val computes and reg,#val and compares the result with 0.

strh reg,[dest] stores the low half word number in reg at the address given by dest.