W90210F Datasheet, PDF(49/67 Page) Winbond – PA-RISC EMBEDDED CONTROLLER

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W90210F Datasheet, PDF (49/67 Pages) Winbond – PA-RISC EMBEDDED CONTROLLER

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W90210F

Halfword parallel subtract

Format:

HSUB,cmplt r1,r2,t

0:5

5:10

11:15

26 27:31

r2 r1 0 0 1 sat 0 t

5 5 3 1 4 21 5

Purpose: To subtract multiple pairs of halfwords in parallel with optional saturation.

HSUB

Description:The corresponding halfwords of GR r2 are subtracted from the halfwords of GR r1 in

parallel. Optional saturation is performed, which forces each halfword result to either the

maximum or the minimum value, if the result would have been out of the range of the target

format. The halfword results are placed in GR t.

The completer, cmplt, determines whether modular, signed-saturation, or unsigned-

saturation arithmetic is performed. When no completer is specified (sat=3) modular

arithmetic is performed. The completer "ss" (sat=1) designates signed saturation. The

completer "us" (sat=0) indicates unsigned saturation. For signed saturation, all operands are

treated as signed numbers, and the results are signed numbers. For unsigned saturation, the

first operands, from GR r1, are treated as unsigned numbers, the second operands, from GR

r2, are treated as signed numbers, and the results are unsigned numbers.

Operation: GR[t]{0..15} â (GR[r1]{0..15} + â GR[r2]{0..15} + 1);

GR[t]{16..31} â (GR[r1]{16..31} + â GR[r2]{16..31} + 1);

switch (cmplt) {

case ss:

if (max_signed_sat_L)

GR[t]{0..15} â 0x7FFF;

else if (min_signed_sat_L)

GR[t]{0..15} â 0x8000;

if (max_signed_sat_R)

GR[t]{16..31} â 0x7FFF;

else if (min_signed_sat_R)

GR[t]{16..31} â 0x8000;

break;

case ss:

if (max_unsigned_sat_L)

GR[t]{0..15} â 0xFFFF;

else if (min_unsigned_sat_L)

GR[t]{0..15} â 0x0000;

if (max_unsigned_sat_R)

GR[t]{16..31} â 0xFFFF;

else if (min_unsigned_sat_R)

GR[t]{16..31} â 0x0000;

break;

default:

break;

}

Exceptions: None.

/* sat=1 */

/* sat=0 */

/* sat=3 */

The above information is the exclusive intellectual property of Winbond Electronics Corp. and shall not be disclosed, distributed or reproduced without permission from Winbond.

Version 1.4, 10/8/97

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