2.6.3.7.2 Condition Code Suffixes
The instructions that can be conditional have an optional condition code, shown in syntax descriptions as {cond}. Conditional execution requires a preceding IT instruction. An instruction with a condition code is only executed if the condition code flags in the APSR meet the specified condition. The following table shows the condition codes to use. You can use conditional execution with the IT instruction to reduce the number of branch instructions in code. The table also shows the relationship between condition code suffixes and the N, Z, C, and V flags.
| Suffix | Flags | Meaning |
|---|---|---|
| EQ | Z = 1 | Equal |
| NE | Z = 0 | Not equal |
| CS or HS | C = 1 | Higher or same, unsigned |
| CC or LO | C = 0 | Lower, unsigned |
| MI | N = 1 | Negative |
| PL | N = 0 | Positive or zero |
| VS | V = 1 | Overflow |
| VC | V = 0 | No overflow |
| HI | C = 1 and Z = 0 | Higher, unsigned |
| LS | C = 0 or Z = 1 | Lower or same, unsigned |
| GE | N = V | Greater than or equal, signed |
| LT | N != V | Less than, signed |
| GT | Z = 0 and N = V | Greater than, signed |
| LE | Z = 1 and N != V | Less than or equal, signed |
| AL | Can have any value | Always. This is the default when no suffix is specified. |
The following example shows the use of a conditional instruction to find the absolute value of a number. R0 = abs(R1).
Example 1
Absolute value
MOVS R0, R1 ; R0 = R1, setting flags
IT MI ; skipping next instruction if value 0 or positive
RSBMI R0, R0, #0 ; If negative, R0 = -R0
The following example shows the use of conditional instructions to update the value of R4 if the signed values R0 is greater than R1 and R2 is greater than R3.
Example 2
Compare and update value
CMP R0, R1 ; Compare R0 and R1, setting flags
ITT GT ; Skip next two instructions unless GT condition holds
CMPGT R2, R3 ; If 'greater than', compare R2 and R3, setting flags
MOVGT R4, R5 ; If still 'greater than', do R4 = R5