Atmel SAM4S Series, Preliminary Data Sheet

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133
11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
11.6.5.24 USUB16 and USUB8
Unsigned Subtract 16 and Unsigned Subtract 8
Syntax
op{cond}{Rd,} Rn, Rm
where:
Operation
Use these instructions to subtract 16-bit and 8-bit data before writing the result to the destination
register:
The
USUB16
instruction:
1. Subtracts each halfword from the second operand register from the corresponding half-
word of the first operand register.
2. Writes the unsigned result in the corresponding halfwords of the destination register.
The
USUB8
instruction:
1. Subtracts each byte of the second operand register from the corresponding byte of the
first operand register.
2. Writes the unsigned byte result in the corresponding byte of the destination register.
Restrictions
Do not use SP and do not use PC
.
Condition Flags
These instructions do not change the flags.
Examples
USUB16 R1, R0 ; Subtracts halfwords in R0 from corresponding halfword of R1
; writes to corresponding halfword in R1USUB8 R4, R0, R5
; Subtracts bytes of R5 from corresponding byte in R0 and
; writes to the corresponding byte in R4.
op is any of:
USUB16 Unsigned Subtract 16.
USUB8
Unsigned Subtract 8.
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.