Power ISA™ Version 2.03 - Power.org

Version 2.03
5.9.1.2 Vector Integer Subtract Instructions
Vector Subtract and Write Carry-Out
Unsigned Word
VX-form
Vector Subtract Signed Byte Saturate
VX-form
vsubcuw
VRT,VRA,VRB
vsubsbs
VRT,VRA,VRB
4 VRT VRA VRB 1408
0 6 11 16 21 31
do i=0 to 127 by 32
aop (VRA) i:i+31
bop (VRB) i:i+31
temp (EXTZ(aop) + int EXTZ(¬bop) + int 1) >> 32
VRT i:i+31 temp & 0x0000_0001
For each vector element i from 0 to 3, do the following.
Unsigned-integer word element i in VRB is subtracted
from unsigned-integer word element i in
VRA. The complement of the borrow out of bit 0 of
the 32-bit difference is zero-extended to 32 bits
and placed into word element i of VRT.
Special Registers Altered:
None
4 VRT VRA VRB 1792
0 6 11 16 21 31
do i=0 to 127 by 8
aop EXTS((VRA) i:i+7 )
bop EXTS((VRB) i:i+7 )
VRT i:i+7
Clamp(aop + int ¬bop + int 1, -128, 127) 24:31
For each vector element i from 0 to 15, do the following.
Signed-integer byte element i in VRB is subtracted
from signed-integer byte element i in VRA.
- If the intermediate result is greater than
127 the result saturates to 127.
- If the intermediate result is less than -128
the result saturates to -128.
The low-order 8 bits of the result are placed into
byte element i of VRT.
Special Registers Altered:
SAT
Vector Subtract Signed Halfword Saturate
VX-form
Vector Subtract Signed Word Saturate
VX-form
vsubshs
VRT,VRA,VRB
vsubsws
VRT,VRA,VRB
4 VRT VRA VRB 1856
0 6 11 16 21 31
do i=0 to 127 by 16
aop EXTS((VRA) i:i+15 )
bop EXTS((VRB) i:i+15 )
VRT i:i+15
Clamp(aop + int ¬bop + int 1, -2 15 , 2 15 -1) 16:31
For each vector element i from 0 to 7, do the following.
Signed-integer halfword element i in VRB is subtracted
from signed-integer halfword element i in
VRA.
- If the intermediate result is greater than
2 15 -1 the result saturates to 2 15 -1.
- If the intermediate result is less than -2 15
the result saturates to -2 15 .
The low-order 16 bits of the result are placed into
halfword element i of VRT.
Special Registers Altered:
SAT
4 VRT VRA VRB 1920
0 6 11 16 21 31
do i=0 to 127 by 32
aop EXTS((VRA) i:i+31 )
bop EXTS((VRB) i:i+31 )
VRT i:i+31 Clamp(aop + int ¬bop + int 1,-2 31 ,2 31 -1)
For each vector element i from 0 to 3, do the following.
Signed-integer word element i in VRB is subtracted
from signed-integer word element i in VRA.
- If the intermediate result is greater than
2 31 -1 the result saturates to 2 31 -1.
- If the intermediate result is less than -2 31
the result saturates to -2 31 .
The low-order 32 bits of the result are placed into
word element i of VRT.
Special Registers Altered:
SAT
158
Power ISA -- Book I