Datasheet

SAM4E [DATASHEET]
Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14
92
 If adding two positive values results in a negative value
 If subtracting a positive value from a negative value generates a positive value
 If subtracting a negative value from a positive value generates a negative value.
The Compare operations are identical to subtracting, for CMP, or adding, for CMN, except that the result is
discarded. See the instruction descriptions for more information.
Note: Most instructions update the status flags only if the S suffix is specified. See the instruction descriptions for more
information.
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. Table 12-16 shows the condition codes to use.
A conditional execution can be used with the IT instruction to reduce the number of branch instructions in code.
Table 12-16 also shows the relationship between condition code suffixes and the N, Z, C, and V flags.
Absolute Value
The example below shows the use of a conditional instruction to find the absolute value of a number. R0 =
ABS(R1).
MOVS R0, R1 ; R0 = R1, setting flags
IT MI ; IT instruction for the negative condition
RSBMI R0, R1, #0 ; If negative, R0 = -R1
Table 12-16. Condition Code Suffixes
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.