Texas Instruments TMS320C67X/C67X+ DSP - Manual (Page 328)

SUB2 Subtract Two 16-Bit Integers on Upper and Lower Register Halves
3-268 Instruction Set SPRU733
Subtract Two 16-Bit Integers on Upper and Lower Register Halves SUB2
Syntax SUB2 (.unit) src1, src2, dst
.unit = .S1 or .S2
Compatibility C62x, C64x, C67x, and C67x+ CPU
Opcode
31 29 28 27 23 22 18 17 13 12 11 6 5 4 3 2 1 0
creg z dst src2 src1 x 0 1 0 0 0 1 1 0 0 0 s p
3 1 5 5 5 1 1 1
Opcode map field used... For operand type... Unit
src1
src2
dst sint
xsint
sint .S1, .S2
Description The upper and lower halves of src2 are subtracted from the upper and lower
halves of src1 and the result is placed in dst. Any borrow from the lower-half
subtraction does not affect the upper-half subtraction. Specifically, the
upper-half of src2 is subtracted from the upper-half of src1 and placed in the
upper-half of dst. The lower-half of src2 is subtracted from the lower-half of
src1 and placed in the lower-half of dst.
31 16 15 0
a_hi a_lo src1
SUB2
b_hi b_lo src2
31 16 15 0
a_hi − b_hi a_lo − b_lo dst