Texas Instruments TMS320C67X/C67X+ DSP manual Subtract Two Signed Integers With Saturation, Ssub

SSUB Subtract Two Signed Integers With Saturation

				Subtract Two Signed Integers With Saturation
SSUB
Syntax					SSUB (.unit) src1, src2, dst
					.unit = .L1 or .L2
Compatibility					C62x, C64x, C67x, and C67x+ CPU
Opcode
31	29	28	27	23		22	18	17	13	12	11	5	4	3	2	1	0

creg

z

dst

src2

src1

x

op

1

1 0 s

p

3 1555171 1

Opcode map field used...	For operand type...	Unit	Opfield
src1	sint	.L1, .L2	000 1111
src2	xsint
dst	sint
src1	xsint	.L1, .L2	001 1111
src2	sint
dst	sint
src1	scst5	.L1, .L2	000 1110
src2	xsint
dst	sint
src1	scst5	.L1, .L2	010 1100
src2	slong
dst	slong

Description	src2 is subtracted from src1 and is saturated to the result size according to the
	following rules:
	1)	If the result is an int and src1 − src2 > 231 − 1, then the result is 231 − 1.
	2)	If the result is an int and src1 − src2 < −231, then the result is −231.
	3)	If the result is a long and src1 − src2 > 239 − 1, then the result is 239 − 1.
	4)	If the result is a long and src1 − src2 < −239, then the result is −239.
	The result is placed in dst. If a saturate occurs, the SAT bit in CSR is set
	one cycle after dst is written.
Execution	if (cond)		src1 −s src2 → dst
	else nop

3-234 Instruction Set SPRU733