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researchv9-SUN3(old)
.data
.asciz "@(#)Fmuld.s 1.1 86/02/03 Copyr 1985 Sun Micro"
.even
.text
| Copyright (c) 1985 by Sun Microsystems, Inc.
#include "fpcrtdefs.h"
/*
* double-precision floating math run-time support
*
* copyright 1981, 1982 Richard E. James III
* translated to SUN idiom 10/11 March 1983 rt
* parameter passing re-done 22 July 1983 rt
*/
ARG2PTR = a0
/*
* ieee double floating divide
* copyright 1981, Richard E. James III
* translated to SUN idiom 10 March 1983 rt
*/
/*
* entry conditions:
* first argument in d0/d1
* second argument on stack
* exit conditions:
* result (8 bytes) in d0/d1
*
* register conventions:
* d0/d1 divisor
* d2/d3 dividend
* d4 count
* d5 sign an exponent
* d6 result exponent
* d6/d7 quotient
*/
SAVEMASK = 0x3f00 | registers d2-d7
RESTMASK = 0xfc
NSAVED = 6*4 | 6 registers * sizeof(register)
RTENTRY(Fdivd)
| save registers and load operands into registers
moveml #0x3f00,sp@- | registers d2-d7
movl d0,d2
movl d1,d3
movl ARG2PTR@+,d0
movl ARG2PTR@ ,d1
| save sign of result
movl d0,d5
eorl d2,d5 | sign of result
clrl d4 | flag for divide
bsrs extrem
| compute resulting exponent
movw d6,d5
subw d7,d5
| do top 30-31 bits of divide (d_rcp will post normalize)
movw #30,d4 | count 30..0
bsr shsub | shift and subtract loop
movl d7,d6 | top of answer
| do next 22 bits of divide
movw #23,d4 | count 23..0 (total = 54-55 bits)
bsr shsub
| put together answer
lsll #8,d7 | line up bottom
orl d3,d2
beqs 1$
bset #1,d7 | sticky bit on if remainder <> 0
1$: lsll #1,d7
roxll #1,d6
| normalize (once), round, check result exp, pack
movl d6,d2 | upper
movl d7,d3 | lower
movw d5,d6 | exponent
addw #1023,d6 | re-bias
jbsr d_nrcp | norm once, rnd, ck, pack
bra dmsign
/*
* round, check for over/underflow, and pack in the exponent.
* d_nrcp does one normalize and then calls d_rcp.
* d_rcp rounds the double value and packs the exponent in,
* catching infinity, zero, and denormalized numbers.
* d_usel puts together the larger argument.
*
* input:
* d2/d3 mantissa (- if norm)
* d6 biased exponent
* (need sign, sticky)
* output:
* d2/d3 most of number, no sign or hidden bit,
* waiting to shift sign in.
* other:
* d4 lost
* d5 unchanged
*/
d_nrcp:
tstl d2
jmi d_rcp | already normalized
subqw #1,d6
lsll #1,d3 | do extra normalize (for mul/div)
roxll #1,d2
jra d_rcp
/*
* subroutine for unpacking one operand, and normalizing a denormalized number
* input:
* d0/d1 number
* output:
* d0/d1 mantissa
* d7.w exponent
* z on iff mantissa is zero_
*
* unchanged:
* d4 bottom = 0xf77
*/
unp: movl d0,d7 | start getting exp
andl #0xfffff,d0 | clear out sign and exp
swap d7
lsrw #(16-1-11),d7
andw d4,d7 | expondnt
bnes 3$ | normal number
| denormalized number or zero:
tstl d0 | upper
bnes 1$
tstl d1 | lower
beqs 3$ |zero
1$: addqw #1,d7
2$: subql #1,d7
lsll #1,d1
roxll #1,d0 | normalize
btst #20,d0
beqs 2$ | loop until normalized
3$: rts
/*
* subroutine for extracting and taking care of 0/GU/INF/NAN.
* input:
* d0/d1, d2/d3
* d4 + for div; - for mod
*
* output:
* d0/d1 (bottom) and d2/d3 (top) converted to
* 000XXXXX/XXXXXXXX
* d6 exponent of top
* d7 exponent of bottom
*
* unchanged:
* d5 sign
*/
extrem:
movw #0x7ff,d4 | mask, sign.l untouched
exg d2,d0
exg d3,d1
bsrs unp | unpack top
exg d0,d2
exg d1,d3
exg d7,d6
beqs topzero | top is zero
cmpw d4,d6
beqs topbig | top is inf or nan
bset #20,d2 | set hidden bit
topzero:bsrs unp | unpack bottom
beqs botzero | bottom is 0
cmpw d4,d7
beqs botbig | bottom is inf or nan
bset #20,d0
lsll #1,d1 | left shift bottom
roxll #1,d0
rts
/*
* EXCEPTION HANDLING
*/
topbig: | top is inf or nan
bsrs unp | unpack bottom
tstl d4
bmis isnan | inf or nan / ...
cmpw d6,d7
beqs isnan | both inf/nan
tstl d2 | top
beqs geninf | inf / ... = inf
bras isnan | nan / ... = nan
botzero:| bottom is 0
tstl d4
bmis gennan | dmod(... 0) = nan
orl d2,d3 | top
beqs gennan | 0/0 = nan
| nonzero/0 = inf
| generate infinity for answer
geninf: movl #0x7ff00000*2,d2 | infinity
bras clrbot
botbig: tstl d0 | bottom = nan, result = nan
bnes isnan
tstl d4
bpls genzero | ... / inf = 0
addqw #4,sp
addw #11,d6 | append sign
jbsr d_norm | normalize
jbsr d_rcp | adjust exp, ck extremes, pack
dmsign: roxll #1,d5 | sign -> x
roxrl #1, d2 | rotate in sign
| answer is now in:
| d2 most significant 32 bits
| d3 least significant 32 bits
dmexit: movl d2,d0
movl d3,d1
| restore registers and split
moveml sp@+,#RESTMASK
RET
| invalid operand/operation
isnan: cmpw d7,d6
bnes 1$ | exponents equal
cmpl d0, d2
1$: bges 2$
movw d7,d6
movl d0,d2
2$: swap d2
lslw #(16-1-11),d6
orw d6,d2 | put back together
swap d2
lsll #1,d2
cmpl #0x7ff00000*2, d2
bhis gotnan | use larger nan
gennan: movl #0x7ff00004*2,d2
tstl d4
bpls gotnan | nan 4 for div
addql #2,d2 | nan 5 for mod
gotnan: clrl d5
bras clrbot
genzero:clrl d2
clrbot: clrl d3
sign: addqw #4,sp
bra dmsign
/*
* the shsub subroutine does a shift-subtract loop
* that is the heart of divide and mod.
* the algorithm is a simple shift and subtract loop,
* but it adds when it overshoots.
* why not use the divs/divu instructions? That approach is slower!
*
* registers:
* d2/d3 current dividend (updated)
* d0/d1 divisor (unchanged)
* d4.w (inpout) number of interations -1, and bit number
* d5/d6 -untouched-
* d7 quotient being devloped (ignored by mod)
*/
shsub:
clrl d7 | quotient
| shift once, see if subtract needed
1$: addl d3,d3
addxl d2,d2 |(64-bit left shift)
cmpl d0,d2
dbge d4,1$ | loop while divident is small
| tally quotient and subtract
bset d4,d7 | quotient bit
subl d1,d3
subxl d0,d2 | 64-bit subtract
dbmi d4,1$ | loop (d4) times
| now one of three things has happeded:
| 1. count exhausted and extra subtract done (first DB hit count)
| 2. count exhausted in second DB
| 3. overshot because compare didn't check lower parts
bpls 2$ | case 2
addl d1,d3 | take care of overshoot
addxl d0,d2
bclr d4,d7
tstw d4
dblt d4,1$ | case 3
| case 1
2$: rts
/*
* ieee double floating multiply
* copyright 1981, Richard E. James III
* translated to SUN idiom 10 March 1983 rt
*/
/*
Revised to do correct IEEE rounding by dgh 24 Aug 84
* Conventions in the main multiplication section are as follows:
* r is the argument passed in the registers d0/d1
* s is the argument passed on the stack, saved in a0/a1
* while multiplying
* r1,r2,r3,r4 are the 16 bit components of r in descending order
* s1,s2,s3,s4 are the 16 bit components of s
* r is kept in d0 and d1, sometimes with words swapped
* s is kept in a0 and a1 unchanged
* the product is kept in d2/d3/d4/d5
* d6 contains a current partial product
* d7 contains a current partial product
* d7 contains 0 when needed for addxl
* a2 saves the sign and exponent of the result
*
* At the end, d4 and d5 if nonzero are jammed into lsb of d3.
*/
/*
* entry conditions:
* first argument in d0/d1
* second argument on stack
* exit conditions:
* result (8 bytes) in d0/d1
*
* register conventions:
* d0-d3 operands or pieces of result
* d5 exponent of larger
* d5 temp for multiplying
* d6 sign and exponent
* d7 exponent of smaller
* d7 zero
*/
SAVEMASK = 0x3fe0 | registers d2-d7,a0-a2
RESTMASK = 0x7fc
NSAVED = 6*4 | 6 registers * sizeof(register)
SAVE03 = 0xf000 | registers d0-d3
FETCH03 = 0x000f
RTENTRY(Fsqrd)
moveml #SAVEMASK,sp@- | registers d2-d7
movel d0,d2
movel d1,d3
bras Fmuld2
RTENTRY(Fmuld)
| save registers and load operands into registers
moveml #SAVEMASK,sp@- | registers d2-d7
movl ARG2PTR@+,d2
movl ARG2PTR@ ,d3
Fmuld2:
| save sign of result
movl d0,d5
eorl d2,d5 | sign of result
asll #1,d0 | toss sign
asll #1,d2 | EEmmmm0
cmpl d2,d0
| order operands (exponents at least)
blss eswap
exg d0,d2 | d2/d3 = larger
exg d1,d3
| extract and check exponents
eswap: jbsr d_exte
movw d6,d5 | larger exp
movl d5,d6
addw d7,d6 | result exp (and sign)
cmpw #0x7ff,d5 | check larger
jeq ovfl | inf or nan
tstw d7
jeq ufl | 0 or gradual underflow
| set hidden bits
bset #31,d0
back: bset #31,d2
| Main multiply sequence.
movl d2,a0 | a0 gets s1s2.
movl d3,a1 | a1 gets s3s4.
movl d6,a2 | a2 saves sign and exponent of result.
movl a0,d3 | d3 gets s1s2.
swap d3 | d3 gets s2s1.
movw d3,d4 | d4 gets s1.
mulu d1,d4 | d4 gets r4*s1.
mulu d0,d3 | d3 gets r2*s1.
clrw d2 | d2 gets 0; only gets carries in this phase.
movl a1,d6 | d6 gets s3s4.
swap d6 | d6 gets s4s3.
movw d6,d5 | d5 gets s3.
jeq s3zero | Branch if s3=0 to avoid following.
mulu d1,d5 | d5 gets r4*s3.
movw d6,d7 | d7 gets s3.
mulu d0,d7 | d7 gets r2*s3.
addl d7,d4
clrl d7 | Make a zero for addx.
addxl d7,d3
addxw d7,d2
phase3:
swap d0 | d0 gets r2r1.
swap d1 | d1 gets r4r3.
movw a0,d6 | d6 gets s2.
beqs 4$ | Skip following if s2=0.
movw d6,d7 | d7 gets s2.
mulu d0,d6 | d6 gets r1*s2.
mulu d1,d7 | d7 gets r3*s2.
addl d7,d4
addxl d6,d3
clrw d7
addxw d7,d2
4$:
movw a1,d6 | d6 gets s4.
beqs 5$ | Skip if s4=0.
movw d6,d7 | d7 gets s4.
mulu d0,d6 | d6 gets r1*s4.
mulu d1,d7 | d7 gets r3*s4.
addl d7,d5
addxl d6,d4
clrl d7
addxl d7,d3
addxw d7,d2
5$:
swap d2 | Exchange order of registers which contain
swap d3 | all the "odd" partial products.
swap d4
swap d5
movw d3,d2 | It's really a 16 bit shift!
movw d4,d3
movw d5,d4
clrw d5
movl a1,d6 | d6 gets s3s4.
swap d6 | d6 gets s4s3.
movw d6,d7 | d7 gets s3.
beqs 6$
mulu d0,d6 | d6 gets r1*s3.
mulu d1,d7 | d7 gets r3*s3.
addl d7,d4
addxl d6,d3
clrl d7
addxl d7,d2
6$:
movl a0,d6 | d6 gets s1s2.
swap d6 | d6 gets s2s1.
movw d6,d7 | d7 gets s1.
mulu d0,d6 | d6 gets r1*s1.
mulu d1,d7 | d7 gets r3*s1.
addl d7,d3
addxl d6,d2
swap d0 | d0 gets r1r2.
swap d1 | d1 gets r3r4.
movw a0,d6 | d6 gets s2.
beqs 8$
movw d6,d7 | d7 gets s2.
mulu d0,d6 | d6 gets r2*s2.
mulu d1,d7 | d7 gets r4*s2.
addl d7,d4
addxl d6,d3
clrl d7
addxl d7,d2
8$:
movw a1,d6 | d6 gets s4.
beqs 9$
movw d6,d7 | d7 gets s4.
mulu d0,d6 | d6 gets r2*s4.
mulu d1,d7 | d7 gets r4*s4.
addl d7,d5
addxl d6,d4
clrl d7
addxl d7,d3
addxl d7,d2
9$:
orl d5,d4
beqs 10$ | Branch if no sticky bits.
bset #0,d3 | Set that sticky!
10$:
movl a2,d6 | Restore sign/exponent of result.
subw #1022,d6 | toss xtra bias
jbsr d_nrcp | norm, rnd, ck, pack
msign: roxll #1,d6
roxrl #1,d2 | append sign
mexit: | answer is now in d2/d3: put in d0/d1
movl d2,d0
movl d3,d1
| restore registers and split
moveml sp@+,#RESTMASK
| slide down return address to pop off junk
RET
s3zero:
clrl d5 | We do need to clear d5 sometime.
jra phase3
| EXCEPTION CASES
ovfl: movl d2,d5 | larger mantissa, if it is nan, use it
orw d7,d5 | smaller exponent
orl d0,d5
orl d1,d5 | smaller value
beqs m_gennan| inf * 0
| else nan*x or inf*nonzero:
movw #0x7ff,d6
jbsr d_usel
bras msign
ufl: movl d0,d7 | mantissa of smaller
orl d1,d7
beqs signed0 | 0*number
normu: subqw #1,d6
lsll #1,d1 | adjust denormalized number
roxll #1,d0
bpls normu
addqw #1,d6
jra back
| (if both are denormalized, answer will be zero anyway)
m_gennan:movl #0x7ff00002,d2
bras mexit
signed0:clrl d2
clrl d3
bras msign
SAVEMASK = 0x3f00
RESTMASK = 0x00fc
EXP = d2
TYPE = d3
/* type values: */
ZERO = 1 | wonderful
GU = 2
PLAIN = 3
INF = 4
NAN = 5
RTENTRY(Fscaleid)
moveml #SAVEMASK,sp@- | state save
jbsr d_unpk
cmpb #PLAIN,TYPE | is it a funny number?
bgts gohome | yes -- return argument
cmpb #ZERO,TYPE
beqs gohome | is zero -- return arg
| normal path through here
movw EXP,d7
extl d7 | d7 gets long exponent.
addl a0@,d7 | d7 gets modified exponent.
bvcs nooflo | Branch if no overflow.
bmis posov | Branch if positive overflow to -.
| Branch if negative overflow to +.
negov:
movw #-2000,EXP
bras gohome
posov:
movw #2000,EXP
bras gohome
nooflo:
cmpl #2000,d7
bges posov
cmpl #-2000,d7
bles negov
movw d7,EXP | Final OK exponent.
gohome:
jbsr d_pack
gone: moveml sp@+,#RESTMASK
RET
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