PM0214 datasheet(101/245 Pages) STMICROELECTRONICS

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PM0214

The STM32 Cortex-M4 instruction set

244

; Adds top halfword of R3 to bottom halfword of R2 and

; writes to top halfword of R7.

3.5.18

UHADD16 and UHADD8

Unsigned halving add 16 and Unsigned halving add 8

Syntax

op{cond}{Rd,} Rn, Rm

where:

•

op is any of:

UHADD16: Unsigned halving add 16.

UHADD8: Unsigned halving add 8.

•

‘cond’ is an optional condition code (see Conditional execution on page 64)

•

‘Rd’ is the destination register

•

‘Rn’ is the register holding the first operand

•

‘Rm’ is the register holding the second operand

Operation

Use these instructions to add 16- and 8-bit data and then to halve the result before writing

the result to the destination register:

The UHADD16 instruction:

Adds each halfword from the first operand to the corresponding halfword of the second

operand.

Shuffles the halfword result by one bit to the right, halving the data.

Writes the unsigned results to the corresponding halfword in the destination register.

The UHADD8 instruction:

Adds each byte of the first operand to the corresponding byte of the second operand.

Shuffles the byte result by one bit to the right, halving the data.

Writes the unsigned results in the corresponding byte in the destination register.

Restrictions

Do not use SP and do not use PC.

Condition flags

These instructions do not change the flags.

Examples

UHADD16 R7, R3

; Adds halfwords in R7 to corresponding halfword of R3 &

; writes halved result to corresponding halfword in R7

UHADD8

R4, R0, R5 ; Adds bytes of R0 to corresponding byte in R5 and writes

; halved result to corresponding byte in R4.

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