Uqasx And Uqsax - ST STM32H7 Series Programming Manual

PM0214
3.7.6

UQASX and UQSAX

Saturating Add and Subtract with Exchange and Saturating Subtract and Add with
Exchange, unsigned.
Syntax
op{cond} {Rd}, Rm, Rn
Where:
•
op' is one of:
UQASX Add and Subtract with Exchange and Saturate.
UQSAX Subtract and Add with Exchange and Saturate.
• 'cond' is an optional condition code (see
•
'Rd' is the destination register.
• 'Rn, Rm' are registers holding the first and second operands.
Operation
The UQASX instruction:
1. Adds the bottom halfword of the source operand with top halfword of second operand.
2. Subtracts the bottom halfword of the second operand from the top highword of the first
operand.
3. Saturates the results of the sum and writes a 16-bit unsigned integer in the range
0 ≤ x ≤ 2
4.
5. Saturates the result of the subtraction and writes a 16-bit unsigned integer in the range
0 ≤ x ≤ 2
The UQSAX instruction:
1. Subtracts the bottom halfword of second operand from top highword of first operand.
2. Adds the bottom halfword of the first operand with the top halfword of the second
operand.
3. Saturates the result of the subtraction and writes a 16-bit unsigned integer in the range
0 ≤ x ≤ 2
4. Saturates the results of the addition and writes a 16-bit unsigned integer in the range 0
≤ x ≤ 2
Restrictions
Do not use SP and do not use PC.
Condition flags
These instructions do not affect the condition code flags.
Examples
UQASX
; from R5, saturates to 32 bits, writes to R0.
16
– 1, where x equals 16, to the top halfword of the destination register.
16
– 1, where x equals 16, to the bottom halfword of the destination register.
16
– 1, where x equals 16, to the top halfword of the destination register.
16
– 1, where x equals 16, to the bottom halfword of the destination register.
R7, R4, R2 ; Adds top halfword of R4 with bottom halfword of R2,
; saturates to 16 bits, writes to top halfword of R7
; Subtracts top halfword of R2 from bottom halfword of
The STM32 Cortex-M4 instruction set
Conditional execution on page
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