ccmp

Conditional Compare (Register)

CCMP <Wn>, <Wm>, #<nzcv>, <cond>

Compares two registers if condition is true.

Pseudocode Operation

if ConditionHolds(cond) then temp ← Wn - Wm; N ← temp[31]; Z ← (temp == 0); C ← NOT(BorrowFrom(Wn, Wm)); V ← SignedOverflow(Wn, -Wm) else N ← nzcv[3]; Z ← nzcv[2]; C ← nzcv[1]; V ← nzcv[0]

Example

CCMP w1, w2, #nzcv, cond

Encoding

Binary Layout

0

31

1

30

1

29

11010010

28:21

Rm

20:16

cond

15:12

0

11

0

10

Rn

9:5

0

4

nzcv

3:0

 

Format Cond Comp

Opcode 0x7A400000

Extension Base

Operands

• Wn
  Reg 1
• Wm
  Reg 2
• nzcv
  Flags
• cond
  Condition

Related

Other forms of ccmp

• ccmp Conditional Compare (Immediate)

More in Base

Reference

View in Arm A64 ISA Reference ↗ Arm A64 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0x7A400800	CCMP <Wn>, #<imm>, #<nzcv>, <cond>		A64		0 | 1 | 1 | 11010010 | imm5 | cond | 1 | 0 | Rn | 0 | nzcv
0xFA400800	CCMP <Xn>, #<imm>, #<nzcv>, <cond>		A64		1 | 1 | 1 | 11010010 | imm5 | cond | 1 | 0 | Rn | 0 | nzcv
0x7A400000	CCMP <Wn>, <Wm>, #<nzcv>, <cond>		A64		0 | 1 | 1 | 11010010 | Rm | cond | 0 | 0 | Rn | 0 | nzcv
0xFA400000	CCMP <Xn>, <Xm>, #<nzcv>, <cond>		A64		1 | 1 | 1 | 11010010 | Rm | cond | 0 | 0 | Rn | 0 | nzcv

Description

Conditional Compare (register) sets the value of the condition flags to the result of the comparison of two registers if the condition is TRUE, and an immediate value otherwise.

Operation

if ConditionHolds(cond) then
    bits(datasize) operand1 = X[n, datasize];
    bits(datasize) operand2 = X[m, datasize];
    operand2 = NOT(operand2);
    (-, flags) = AddWithCarry(operand1, operand2, '1');
PSTATE.<N,Z,C,V> = flags;