NEG

NEG

Negate (DALU)

Operation

Assembler Syntax

0 – Dn → Dn

NEG Dn

NEG

Description

NEG Dn

Negates the contents of a source data register (Dn) and stores the 40-bit two’s complement result in a destination data register (Dn).

Status and Conditions that Affect Instruction

Register Address

Bit Name

Description

SR[2]

SM

If set, selects 32-bit arithmetic saturation mode.

SR[5:4]

S[1:0]

Scaling mode bits determine which bits in the result are used in the

 

 

Ln bit calculation.

Status and Conditions Changed by Instruction

Register Address

Bit Name

Description

Ln

L

If not in arithmetic saturation mode (SR [SM] = 0), calculates and

 

 

updates the Ln bit in the destination register. If in arithmetic

 

 

saturation mode (SR [SM] = 1), clears the Ln bit in the destination

 

 

register.

EMR[2]

DOVF

Set if the result cannot be represented in 40 bits, or if the result

 

 

saturates to 32 bits in saturation mode.

Example

neg d3

Register/Memory Address

SR

L3:D3

EMR

Before

$00E0 0000

$0:$00 0765 1235

After

$0:$FF F89A EDCB

$0000 0000

0000 0111 0110 0101 0001 0010 0011 0101 invert 1111 1000 1001 1010 1110 1101 1100 1010 add one 1111 1000 1001 1010 1110 1101 1100 1011

SC140 DSP Core Reference Manual

A-331

Page 645
Image 645
Freescale Semiconductor SC140 specifications Negate Dalu, Neg d3, NEG Dn