W90221X Winbond Electronics Corp America, W90221X Datasheet - Page 198

• Manufacturer Part Number: W90221X
• Description: Pa-risc Embedded Controller
• Manufacturer: Winbond Electronics Corp America

APPENDIX C : MULTIPLIER EXTENDED INSTRUCTION SET
Halfword Multiply
Format:
Purpose: To multiply corresponding 16-bit sign halfword of two general registers.
Description: The corresponding 16-bit sign halfwords of GR[r1] and GR[r2] are
arithme-tically multiplied. The multiply result is placed in 32-bit LO accumulate
register and GR[t] register. The bit in AIR[25] which indicates operating in integer or
fraction mode determines the high-order or low-order 16 bits of GR[r1], GR[r2] will be
as the two operands.
performed, the completer specified by "r" indicates operating in rounding mode, the
multiply result can be truncated the lower 16 bits when the least 16th bit is zero. IF
the the least 16th bit is one, add one with the high-order 48 bits and truncate the low-
order 16 bits.
Operation:
Integer mode operation (AIR[25] = 0) :
switch (cmplt) {
sign_ext(GR[r2]{16:31})+16h8000);
sign_ext(GR[r2]{16:31})+16h8000);
sign_ext(GR[r2]{16:31}));
sign_ext(GR[r2]{16:31}));
}
Fraction mode operation (AIR[25] = 1):
switch(cmplt){
W90221X version 0.6
05
The completer, cmplt, determines multiplication in rounding or unrounding mode is
0:5
6
default : (r=0, unrounding mode){
case r : (r=1, rounding mode){
case r : (r=1, rounding mode){
r2
6:10
5
LO{0:31}
LO{0:31}
GR[t]{0:31}
break;
}
GR[t]{0:31}
break;
}
HMUL, cmplt
r1
11:15
5
~
16:18
3
r1,r2,t
r
19
1
1
20
01
1
(sign_ext(GR[r1]{16:31})
(sign_ext(GR[r1]{16:31})
21:25
(sign_ext(GR[r1]{16:31})
(sign_ext(GR[r1]{16:31})
~
5
t
26
1
27:31
HMUL
5
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