Atmel SAM4S Series, Preliminary Data Sheet

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122
11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
11.6.5.13 SSUB16 and SSUB8
Signed Subtract 16 and Signed Subtract 8
Syntax
op{cond}{Rd,} Rn, Rm
where:
Operation
Use these instructions to change endianness of data:
The
SSUB16
instruction:
1. Subtracts each halfword from the second operand from the corresponding halfword of
the first operand
2. Writes the difference result of two signed halfwords in the corresponding halfword of
the destination register.
The
SSUB8
instruction:
1. Subtracts each byte of the second operand from the corresponding byte of the first
operand
2. Writes the difference result of four signed bytes in the corresponding byte of the desti-
nation register.
Restrictions
Do not use SP and do not use PC
.
Condition Flags
These instructions do not change the flags.
Examples
SSUB16 R1, R0 ; Subtracts halfwords in R0 from corresponding halfword
; of R1 and writes to corresponding halfword of R1
SSUB8 R4, R0, R5 ; Subtracts bytes of R5 from corresponding byte in
; R0, and writes to corresponding byte of R4.
op is any of:
SSUB16 Performs two 16-bit signed integer subtractions.
SSUB8
Performs four 8-bit signed integer subtractions.
cond is an optional condition code, see “Conditional Execution” .
Rd is the destination register.
Rn is the first operand register.
Rm is the second operand register.