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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [runtime/] [softfloat64.go] - Blame information for rev 867

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// Copyright 2010 The Go Authors.  All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
 
// Software IEEE754 64-bit floating point.
// Only referred to (and thus linked in) by arm port
// and by gotest in this directory.
 
package runtime
 
const (
        mantbits64 uint = 52
        expbits64  uint = 11
        bias64          = -1<<(expbits64-1) + 1
 
        nan64 uint64 = (1<
        inf64 uint64 = (1<
        neg64 uint64 = 1 << (expbits64 + mantbits64)
 
        mantbits32 uint = 23
        expbits32  uint = 8
        bias32          = -1<<(expbits32-1) + 1
 
        nan32 uint32 = (1<
        inf32 uint32 = (1<
        neg32 uint32 = 1 << (expbits32 + mantbits32)
)
 
func funpack64(f uint64) (sign, mant uint64, exp int, inf, nan bool) {
        sign = f & (1 << (mantbits64 + expbits64))
        mant = f & (1<
        exp = int(f>>mantbits64) & (1<
 
        switch exp {
        case 1<
                if mant != 0 {
                        nan = true
                        return
                }
                inf = true
                return
 
        case 0:
                // denormalized
                if mant != 0 {
                        exp += bias64 + 1
                        for mant < 1<
                                mant <<= 1
                                exp--
                        }
                }
 
        default:
                // add implicit top bit
                mant |= 1 << mantbits64
                exp += bias64
        }
        return
}
 
func funpack32(f uint32) (sign, mant uint32, exp int, inf, nan bool) {
        sign = f & (1 << (mantbits32 + expbits32))
        mant = f & (1<
        exp = int(f>>mantbits32) & (1<
 
        switch exp {
        case 1<
                if mant != 0 {
                        nan = true
                        return
                }
                inf = true
                return
 
        case 0:
                // denormalized
                if mant != 0 {
                        exp += bias32 + 1
                        for mant < 1<
                                mant <<= 1
                                exp--
                        }
                }
 
        default:
                // add implicit top bit
                mant |= 1 << mantbits32
                exp += bias32
        }
        return
}
 
func fpack64(sign, mant uint64, exp int, trunc uint64) uint64 {
        mant0, exp0, trunc0 := mant, exp, trunc
        if mant == 0 {
                return sign
        }
        for mant < 1<
                mant <<= 1
                exp--
        }
        for mant >= 4<
                trunc |= mant & 1
                mant >>= 1
                exp++
        }
        if mant >= 2<
                if mant&1 != 0 && (trunc != 0 || mant&2 != 0) {
                        mant++
                        if mant >= 4<
                                mant >>= 1
                                exp++
                        }
                }
                mant >>= 1
                exp++
        }
        if exp >= 1<
                return sign ^ inf64
        }
        if exp < bias64+1 {
                if exp < bias64-int(mantbits64) {
                        return sign | 0
                }
                // repeat expecting denormal
                mant, exp, trunc = mant0, exp0, trunc0
                for exp < bias64 {
                        trunc |= mant & 1
                        mant >>= 1
                        exp++
                }
                if mant&1 != 0 && (trunc != 0 || mant&2 != 0) {
                        mant++
                }
                mant >>= 1
                exp++
                if mant < 1<
                        return sign | mant
                }
        }
        return sign | uint64(exp-bias64)<
}
 
func fpack32(sign, mant uint32, exp int, trunc uint32) uint32 {
        mant0, exp0, trunc0 := mant, exp, trunc
        if mant == 0 {
                return sign
        }
        for mant < 1<
                mant <<= 1
                exp--
        }
        for mant >= 4<
                trunc |= mant & 1
                mant >>= 1
                exp++
        }
        if mant >= 2<
                if mant&1 != 0 && (trunc != 0 || mant&2 != 0) {
                        mant++
                        if mant >= 4<
                                mant >>= 1
                                exp++
                        }
                }
                mant >>= 1
                exp++
        }
        if exp >= 1<
                return sign ^ inf32
        }
        if exp < bias32+1 {
                if exp < bias32-int(mantbits32) {
                        return sign | 0
                }
                // repeat expecting denormal
                mant, exp, trunc = mant0, exp0, trunc0
                for exp < bias32 {
                        trunc |= mant & 1
                        mant >>= 1
                        exp++
                }
                if mant&1 != 0 && (trunc != 0 || mant&2 != 0) {
                        mant++
                }
                mant >>= 1
                exp++
                if mant < 1<
                        return sign | mant
                }
        }
        return sign | uint32(exp-bias32)<
}
 
func fadd64(f, g uint64) uint64 {
        fs, fm, fe, fi, fn := funpack64(f)
        gs, gm, ge, gi, gn := funpack64(g)
 
        // Special cases.
        switch {
        case fn || gn: // NaN + x or x + NaN = NaN
                return nan64
 
        case fi && gi && fs != gs: // +Inf + -Inf or -Inf + +Inf = NaN
                return nan64
 
        case fi: // ±Inf + g = ±Inf
                return f
 
        case gi: // f + ±Inf = ±Inf
                return g
 
        case fm == 0 && gm == 0 && fs != 0 && gs != 0: // -0 + -0 = -0
                return f
 
        case fm == 0: // 0 + g = g but 0 + -0 = +0
                if gm == 0 {
                        g ^= gs
                }
                return g
 
        case gm == 0: // f + 0 = f
                return f
 
        }
 
        if fe < ge || fe == ge && fm < gm {
                f, g, fs, fm, fe, gs, gm, ge = g, f, gs, gm, ge, fs, fm, fe
        }
 
        shift := uint(fe - ge)
        fm <<= 2
        gm <<= 2
        trunc := gm & (1<
        gm >>= shift
        if fs == gs {
                fm += gm
        } else {
                fm -= gm
                if trunc != 0 {
                        fm--
                }
        }
        if fm == 0 {
                fs = 0
        }
        return fpack64(fs, fm, fe-2, trunc)
}
 
func fsub64(f, g uint64) uint64 {
        return fadd64(f, fneg64(g))
}
 
func fneg64(f uint64) uint64 {
        return f ^ (1 << (mantbits64 + expbits64))
}
 
func fmul64(f, g uint64) uint64 {
        fs, fm, fe, fi, fn := funpack64(f)
        gs, gm, ge, gi, gn := funpack64(g)
 
        // Special cases.
        switch {
        case fn || gn: // NaN * g or f * NaN = NaN
                return nan64
 
        case fi && gi: // Inf * Inf = Inf (with sign adjusted)
                return f ^ gs
 
        case fi && gm == 0, fm == 0 && gi: // 0 * Inf = Inf * 0 = NaN
                return nan64
 
        case fm == 0: // 0 * x = 0 (with sign adjusted)
                return f ^ gs
 
        case gm == 0: // x * 0 = 0 (with sign adjusted)
                return g ^ fs
        }
 
        // 53-bit * 53-bit = 107- or 108-bit
        lo, hi := mullu(fm, gm)
        shift := mantbits64 - 1
        trunc := lo & (1<
        mant := hi<<(64-shift) | lo>>shift
        return fpack64(fs^gs, mant, fe+ge-1, trunc)
}
 
func fdiv64(f, g uint64) uint64 {
        fs, fm, fe, fi, fn := funpack64(f)
        gs, gm, ge, gi, gn := funpack64(g)
 
        // Special cases.
        switch {
        case fn || gn: // NaN / g = f / NaN = NaN
                return nan64
 
        case fi && gi: // ±Inf / ±Inf = NaN
                return nan64
 
        case !fi && !gi && fm == 0 && gm == 0: // 0 / 0 = NaN
                return nan64
 
        case fi, !gi && gm == 0: // Inf / g = f / 0 = Inf
                return fs ^ gs ^ inf64
 
        case gi, fm == 0: // f / Inf = 0 / g = Inf
                return fs ^ gs ^ 0
        }
        _, _, _, _ = fi, fn, gi, gn
 
        // 53-bit<<54 / 53-bit = 53- or 54-bit.
        shift := mantbits64 + 2
        q, r := divlu(fm>>(64-shift), fm<
        return fpack64(fs^gs, q, fe-ge-2, r)
}
 
func f64to32(f uint64) uint32 {
        fs, fm, fe, fi, fn := funpack64(f)
        if fn {
                return nan32
        }
        fs32 := uint32(fs >> 32)
        if fi {
                return fs32 ^ inf32
        }
        const d = mantbits64 - mantbits32 - 1
        return fpack32(fs32, uint32(fm>>d), fe-1, uint32(fm&(1<
}
 
func f32to64(f uint32) uint64 {
        const d = mantbits64 - mantbits32
        fs, fm, fe, fi, fn := funpack32(f)
        if fn {
                return nan64
        }
        fs64 := uint64(fs) << 32
        if fi {
                return fs64 ^ inf64
        }
        return fpack64(fs64, uint64(fm)<
}
 
func fcmp64(f, g uint64) (cmp int, isnan bool) {
        fs, fm, _, fi, fn := funpack64(f)
        gs, gm, _, gi, gn := funpack64(g)
 
        switch {
        case fn, gn: // flag NaN
                return 0, true
 
        case !fi && !gi && fm == 0 && gm == 0: // ±0 == ±0
                return 0, false
 
        case fs > gs: // f < 0, g > 0
                return -1, false
 
        case fs < gs: // f > 0, g < 0
                return +1, false
 
        // Same sign, not NaN.
        // Can compare encodings directly now.
        // Reverse for sign.
        case fs == 0 && f < g, fs != 0 && f > g:
                return -1, false
 
        case fs == 0 && f > g, fs != 0 && f < g:
                return +1, false
        }
 
        // f == g
        return 0, false
}
 
func f64toint(f uint64) (val int64, ok bool) {
        fs, fm, fe, fi, fn := funpack64(f)
 
        switch {
        case fi, fn: // NaN
                return 0, false
 
        case fe < -1: // f < 0.5
                return 0, false
 
        case fe > 63: // f >= 2^63
                if fs != 0 && fm == 0 { // f == -2^63
                        return -1 << 63, true
                }
                if fs != 0 {
                        return 0, false
                }
                return 0, false
        }
 
        for fe > int(mantbits64) {
                fe--
                fm <<= 1
        }
        for fe < int(mantbits64) {
                fe++
                fm >>= 1
        }
        val = int64(fm)
        if fs != 0 {
                val = -val
        }
        return val, true
}
 
func fintto64(val int64) (f uint64) {
        fs := uint64(val) & (1 << 63)
        mant := uint64(val)
        if fs != 0 {
                mant = -mant
        }
        return fpack64(fs, mant, int(mantbits64), 0)
}
 
// 64x64 -> 128 multiply.
// adapted from hacker's delight.
func mullu(u, v uint64) (lo, hi uint64) {
        const (
                s    = 32
                mask = 1<
        )
        u0 := u & mask
        u1 := u >> s
        v0 := v & mask
        v1 := v >> s
        w0 := u0 * v0
        t := u1*v0 + w0>>s
        w1 := t & mask
        w2 := t >> s
        w1 += u0 * v1
        return u * v, u1*v1 + w2 + w1>>s
}
 
// 128/64 -> 64 quotient, 64 remainder.
// adapted from hacker's delight
func divlu(u1, u0, v uint64) (q, r uint64) {
        const b = 1 << 32
 
        if u1 >= v {
                return 1<<64 - 1, 1<<64 - 1
        }
 
        // s = nlz(v); v <<= s
        s := uint(0)
        for v&(1<<63) == 0 {
                s++
                v <<= 1
        }
 
        vn1 := v >> 32
        vn0 := v & (1<<32 - 1)
        un32 := u1<>(64-s)
        un10 := u0 << s
        un1 := un10 >> 32
        un0 := un10 & (1<<32 - 1)
        q1 := un32 / vn1
        rhat := un32 - q1*vn1
 
again1:
        if q1 >= b || q1*vn0 > b*rhat+un1 {
                q1--
                rhat += vn1
                if rhat < b {
                        goto again1
                }
        }
 
        un21 := un32*b + un1 - q1*v
        q0 := un21 / vn1
        rhat = un21 - q0*vn1
 
again2:
        if q0 >= b || q0*vn0 > b*rhat+un0 {
                q0--
                rhat += vn1
                if rhat < b {
                        goto again2
                }
        }
 
        return q1*b + q0, (un21*b + un0 - q0*v) >> s
}
 
// callable from C
 
func fadd64c(f, g uint64, ret *uint64)            { *ret = fadd64(f, g) }
func fsub64c(f, g uint64, ret *uint64)            { *ret = fsub64(f, g) }
func fmul64c(f, g uint64, ret *uint64)            { *ret = fmul64(f, g) }
func fdiv64c(f, g uint64, ret *uint64)            { *ret = fdiv64(f, g) }
func fneg64c(f uint64, ret *uint64)               { *ret = fneg64(f) }
func f32to64c(f uint32, ret *uint64)              { *ret = f32to64(f) }
func f64to32c(f uint64, ret *uint32)              { *ret = f64to32(f) }
func fcmp64c(f, g uint64, ret *int, retnan *bool) { *ret, *retnan = fcmp64(f, g) }
func fintto64c(val int64, ret *uint64)            { *ret = fintto64(val) }
func f64tointc(f uint64, ret *int64, retok *bool) { *ret, *retok = f64toint(f) }

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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [runtime/] [softfloat64.go] - Blame information for rev 867

Line No.	Rev	Author	Line
1	747	jeremybenn	`// Copyright 2010 The Go Authors. All rights reserved.`
2			`// Use of this source code is governed by a BSD-style`
3			`// license that can be found in the LICENSE file.`
4
5			`// Software IEEE754 64-bit floating point.`
6			`// Only referred to (and thus linked in) by arm port`
7			`// and by gotest in this directory.`
8
9			`package runtime`
10
11			`const (`
12			`mantbits64 uint = 52`
13			`expbits64 uint = 11`
14			`bias64 = -1<<(expbits64-1) + 1`
15
16			`nan64 uint64 = (1<`
17			`inf64 uint64 = (1<`
18			`neg64 uint64 = 1 << (expbits64 + mantbits64)`
19
20			`mantbits32 uint = 23`
21			`expbits32 uint = 8`
22			`bias32 = -1<<(expbits32-1) + 1`
23
24			`nan32 uint32 = (1<`
25			`inf32 uint32 = (1<`
26			`neg32 uint32 = 1 << (expbits32 + mantbits32)`
27			`)`
28
29			`func funpack64(f uint64) (sign, mant uint64, exp int, inf, nan bool) {`
30			`sign = f & (1 << (mantbits64 + expbits64))`
31			`mant = f & (1<`
32			`exp = int(f>>mantbits64) & (1<`
33
34			`switch exp {`
35			`case 1<`
36			`if mant != 0 {`
37			`nan = true`
38			`return`
39			`}`
40			`inf = true`
41			`return`
42
43			`case 0:`
44			`// denormalized`
45			`if mant != 0 {`
46			`exp += bias64 + 1`
47			`for mant < 1<`
48			`mant <<= 1`
49			`exp--`
50			`}`
51			`}`
52
53			`default:`
54			`// add implicit top bit`
55			`mant \|= 1 << mantbits64`
56			`exp += bias64`
57			`}`
58			`return`
59			`}`
60
61			`func funpack32(f uint32) (sign, mant uint32, exp int, inf, nan bool) {`
62			`sign = f & (1 << (mantbits32 + expbits32))`
63			`mant = f & (1<`
64			`exp = int(f>>mantbits32) & (1<`
65
66			`switch exp {`
67			`case 1<`
68			`if mant != 0 {`
69			`nan = true`
70			`return`
71			`}`
72			`inf = true`
73			`return`
74
75			`case 0:`
76			`// denormalized`
77			`if mant != 0 {`
78			`exp += bias32 + 1`
79			`for mant < 1<`
80			`mant <<= 1`
81			`exp--`
82			`}`
83			`}`
84
85			`default:`
86			`// add implicit top bit`
87			`mant \|= 1 << mantbits32`
88			`exp += bias32`
89			`}`
90			`return`
91			`}`
92
93			`func fpack64(sign, mant uint64, exp int, trunc uint64) uint64 {`
94			`mant0, exp0, trunc0 := mant, exp, trunc`
95			`if mant == 0 {`
96			`return sign`
97			`}`
98			`for mant < 1<`
99			`mant <<= 1`
100			`exp--`
101			`}`
102			`for mant >= 4<`
103			`trunc \|= mant & 1`
104			`mant >>= 1`
105			`exp++`
106			`}`
107			`if mant >= 2<`
108			`if mant&1 != 0 && (trunc != 0 \|\| mant&2 != 0) {`
109			`mant++`
110			`if mant >= 4<`
111			`mant >>= 1`
112			`exp++`
113			`}`
114			`}`
115			`mant >>= 1`
116			`exp++`
117			`}`
118			`if exp >= 1<`
119			`return sign ^ inf64`
120			`}`
121			`if exp < bias64+1 {`
122			`if exp < bias64-int(mantbits64) {`
123			`return sign \| 0`
124			`}`
125			`// repeat expecting denormal`
126			`mant, exp, trunc = mant0, exp0, trunc0`
127			`for exp < bias64 {`
128			`trunc \|= mant & 1`
129			`mant >>= 1`
130			`exp++`
131			`}`
132			`if mant&1 != 0 && (trunc != 0 \|\| mant&2 != 0) {`
133			`mant++`
134			`}`
135			`mant >>= 1`
136			`exp++`
137			`if mant < 1<`
138			`return sign \| mant`
139			`}`
140			`}`
141			`return sign \| uint64(exp-bias64)<`
142			`}`
143
144			`func fpack32(sign, mant uint32, exp int, trunc uint32) uint32 {`
145			`mant0, exp0, trunc0 := mant, exp, trunc`
146			`if mant == 0 {`
147			`return sign`
148			`}`
149			`for mant < 1<`
150			`mant <<= 1`
151			`exp--`
152			`}`
153			`for mant >= 4<`
154			`trunc \|= mant & 1`
155			`mant >>= 1`
156			`exp++`
157			`}`
158			`if mant >= 2<`
159			`if mant&1 != 0 && (trunc != 0 \|\| mant&2 != 0) {`
160			`mant++`
161			`if mant >= 4<`
162			`mant >>= 1`
163			`exp++`
164			`}`
165			`}`
166			`mant >>= 1`
167			`exp++`
168			`}`
169			`if exp >= 1<`
170			`return sign ^ inf32`
171			`}`
172			`if exp < bias32+1 {`
173			`if exp < bias32-int(mantbits32) {`
174			`return sign \| 0`
175			`}`
176			`// repeat expecting denormal`
177			`mant, exp, trunc = mant0, exp0, trunc0`
178			`for exp < bias32 {`
179			`trunc \|= mant & 1`
180			`mant >>= 1`
181			`exp++`
182			`}`
183			`if mant&1 != 0 && (trunc != 0 \|\| mant&2 != 0) {`
184			`mant++`
185			`}`
186			`mant >>= 1`
187			`exp++`
188			`if mant < 1<`
189			`return sign \| mant`
190			`}`
191			`}`
192			`return sign \| uint32(exp-bias32)<`
193			`}`
194
195			`func fadd64(f, g uint64) uint64 {`
196			`fs, fm, fe, fi, fn := funpack64(f)`
197			`gs, gm, ge, gi, gn := funpack64(g)`
198
199			`// Special cases.`
200			`switch {`
201			`case fn \|\| gn: // NaN + x or x + NaN = NaN`
202			`return nan64`
203
204			`case fi && gi && fs != gs: // +Inf + -Inf or -Inf + +Inf = NaN`
205			`return nan64`
206
207			`case fi: // ±Inf + g = ±Inf`
208			`return f`
209
210			`case gi: // f + ±Inf = ±Inf`
211			`return g`
212
213			`case fm == 0 && gm == 0 && fs != 0 && gs != 0: // -0 + -0 = -0`
214			`return f`
215
216			`case fm == 0: // 0 + g = g but 0 + -0 = +0`
217			`if gm == 0 {`
218			`g ^= gs`
219			`}`
220			`return g`
221
222			`case gm == 0: // f + 0 = f`
223			`return f`
224
225			`}`
226
227			`if fe < ge \|\| fe == ge && fm < gm {`
228			`f, g, fs, fm, fe, gs, gm, ge = g, f, gs, gm, ge, fs, fm, fe`
229			`}`
230
231			`shift := uint(fe - ge)`
232			`fm <<= 2`
233			`gm <<= 2`
234			`trunc := gm & (1<`
235			`gm >>= shift`
236			`if fs == gs {`
237			`fm += gm`
238			`} else {`
239			`fm -= gm`
240			`if trunc != 0 {`
241			`fm--`
242			`}`
243			`}`
244			`if fm == 0 {`
245			`fs = 0`
246			`}`
247			`return fpack64(fs, fm, fe-2, trunc)`
248			`}`
249
250			`func fsub64(f, g uint64) uint64 {`
251			`return fadd64(f, fneg64(g))`
252			`}`
253
254			`func fneg64(f uint64) uint64 {`
255			`return f ^ (1 << (mantbits64 + expbits64))`
256			`}`
257
258			`func fmul64(f, g uint64) uint64 {`
259			`fs, fm, fe, fi, fn := funpack64(f)`
260			`gs, gm, ge, gi, gn := funpack64(g)`
261
262			`// Special cases.`
263			`switch {`
264			`case fn \|\| gn: // NaN * g or f * NaN = NaN`
265			`return nan64`
266
267			`case fi && gi: // Inf * Inf = Inf (with sign adjusted)`
268			`return f ^ gs`
269
270			`case fi && gm == 0, fm == 0 && gi: // 0 * Inf = Inf * 0 = NaN`
271			`return nan64`
272
273			`case fm == 0: // 0 * x = 0 (with sign adjusted)`
274			`return f ^ gs`
275
276			`case gm == 0: // x * 0 = 0 (with sign adjusted)`
277			`return g ^ fs`
278			`}`
279
280			`// 53-bit * 53-bit = 107- or 108-bit`
281			`lo, hi := mullu(fm, gm)`
282			`shift := mantbits64 - 1`
283			`trunc := lo & (1<`
284			`mant := hi<<(64-shift) \| lo>>shift`
285			`return fpack64(fs^gs, mant, fe+ge-1, trunc)`
286			`}`
287
288			`func fdiv64(f, g uint64) uint64 {`
289			`fs, fm, fe, fi, fn := funpack64(f)`
290			`gs, gm, ge, gi, gn := funpack64(g)`
291
292			`// Special cases.`
293			`switch {`
294			`case fn \|\| gn: // NaN / g = f / NaN = NaN`
295			`return nan64`
296
297			`case fi && gi: // ±Inf / ±Inf = NaN`
298			`return nan64`
299
300			`case !fi && !gi && fm == 0 && gm == 0: // 0 / 0 = NaN`
301			`return nan64`
302
303			`case fi, !gi && gm == 0: // Inf / g = f / 0 = Inf`
304			`return fs ^ gs ^ inf64`
305
306			`case gi, fm == 0: // f / Inf = 0 / g = Inf`
307			`return fs ^ gs ^ 0`
308			`}`
309			`_, _, _, _ = fi, fn, gi, gn`
310
311			`// 53-bit<<54 / 53-bit = 53- or 54-bit.`
312			`shift := mantbits64 + 2`
313			`q, r := divlu(fm>>(64-shift), fm<`
314			`return fpack64(fs^gs, q, fe-ge-2, r)`
315			`}`
316
317			`func f64to32(f uint64) uint32 {`
318			`fs, fm, fe, fi, fn := funpack64(f)`
319			`if fn {`
320			`return nan32`
321			`}`
322			`fs32 := uint32(fs >> 32)`
323			`if fi {`
324			`return fs32 ^ inf32`
325			`}`
326			`const d = mantbits64 - mantbits32 - 1`
327			`return fpack32(fs32, uint32(fm>>d), fe-1, uint32(fm&(1<`
328			`}`
329
330			`func f32to64(f uint32) uint64 {`
331			`const d = mantbits64 - mantbits32`
332			`fs, fm, fe, fi, fn := funpack32(f)`
333			`if fn {`
334			`return nan64`
335			`}`
336			`fs64 := uint64(fs) << 32`
337			`if fi {`
338			`return fs64 ^ inf64`
339			`}`
340			`return fpack64(fs64, uint64(fm)<`
341			`}`
342
343			`func fcmp64(f, g uint64) (cmp int, isnan bool) {`
344			`fs, fm, _, fi, fn := funpack64(f)`
345			`gs, gm, _, gi, gn := funpack64(g)`
346
347			`switch {`
348			`case fn, gn: // flag NaN`
349			`return 0, true`
350
351			`case !fi && !gi && fm == 0 && gm == 0: // ±0 == ±0`
352			`return 0, false`
353
354			`case fs > gs: // f < 0, g > 0`
355			`return -1, false`
356
357			`case fs < gs: // f > 0, g < 0`
358			`return +1, false`
359
360			`// Same sign, not NaN.`
361			`// Can compare encodings directly now.`
362			`// Reverse for sign.`
363			`case fs == 0 && f < g, fs != 0 && f > g:`
364			`return -1, false`
365
366			`case fs == 0 && f > g, fs != 0 && f < g:`
367			`return +1, false`
368			`}`
369
370			`// f == g`
371			`return 0, false`
372			`}`
373
374			`func f64toint(f uint64) (val int64, ok bool) {`
375			`fs, fm, fe, fi, fn := funpack64(f)`
376
377			`switch {`
378			`case fi, fn: // NaN`
379			`return 0, false`
380
381			`case fe < -1: // f < 0.5`
382			`return 0, false`
383
384			`case fe > 63: // f >= 2^63`
385			`if fs != 0 && fm == 0 { // f == -2^63`
386			`return -1 << 63, true`
387			`}`
388			`if fs != 0 {`
389			`return 0, false`
390			`}`
391			`return 0, false`
392			`}`
393
394			`for fe > int(mantbits64) {`
395			`fe--`
396			`fm <<= 1`
397			`}`
398			`for fe < int(mantbits64) {`
399			`fe++`
400			`fm >>= 1`
401			`}`
402			`val = int64(fm)`
403			`if fs != 0 {`
404			`val = -val`
405			`}`
406			`return val, true`
407			`}`
408
409			`func fintto64(val int64) (f uint64) {`
410			`fs := uint64(val) & (1 << 63)`
411			`mant := uint64(val)`
412			`if fs != 0 {`
413			`mant = -mant`
414			`}`
415			`return fpack64(fs, mant, int(mantbits64), 0)`
416			`}`
417
418			`// 64x64 -> 128 multiply.`
419			`// adapted from hacker's delight.`
420			`func mullu(u, v uint64) (lo, hi uint64) {`
421			`const (`
422			`s = 32`
423			`mask = 1<`
424			`)`
425			`u0 := u & mask`
426			`u1 := u >> s`
427			`v0 := v & mask`
428			`v1 := v >> s`
429			`w0 := u0 * v0`
430			`t := u1*v0 + w0>>s`
431			`w1 := t & mask`
432			`w2 := t >> s`
433			`w1 += u0 * v1`
434			`return u * v, u1*v1 + w2 + w1>>s`
435			`}`
436
437			`// 128/64 -> 64 quotient, 64 remainder.`
438			`// adapted from hacker's delight`
439			`func divlu(u1, u0, v uint64) (q, r uint64) {`
440			`const b = 1 << 32`
441
442			`if u1 >= v {`
443			`return 1<<64 - 1, 1<<64 - 1`
444			`}`
445
446			`// s = nlz(v); v <<= s`
447			`s := uint(0)`
448			`for v&(1<<63) == 0 {`
449			`s++`
450			`v <<= 1`
451			`}`
452
453			`vn1 := v >> 32`
454			`vn0 := v & (1<<32 - 1)`
455			`un32 := u1<>(64-s)`
456			`un10 := u0 << s`
457			`un1 := un10 >> 32`
458			`un0 := un10 & (1<<32 - 1)`
459			`q1 := un32 / vn1`
460			`rhat := un32 - q1*vn1`
461
462			`again1:`
463			`if q1 >= b \|\| q1vn0 > brhat+un1 {`
464			`q1--`
465			`rhat += vn1`
466			`if rhat < b {`
467			`goto again1`
468			`}`
469			`}`
470
471			`un21 := un32b + un1 - q1v`
472			`q0 := un21 / vn1`
473			`rhat = un21 - q0*vn1`
474
475			`again2:`
476			`if q0 >= b \|\| q0vn0 > brhat+un0 {`
477			`q0--`
478			`rhat += vn1`
479			`if rhat < b {`
480			`goto again2`
481			`}`
482			`}`
483
484			`return q1b + q0, (un21b + un0 - q0*v) >> s`
485			`}`
486
487			`// callable from C`
488
489			`func fadd64c(f, g uint64, ret uint64) { ret = fadd64(f, g) }`
490			`func fsub64c(f, g uint64, ret uint64) { ret = fsub64(f, g) }`
491			`func fmul64c(f, g uint64, ret uint64) { ret = fmul64(f, g) }`
492			`func fdiv64c(f, g uint64, ret uint64) { ret = fdiv64(f, g) }`
493			`func fneg64c(f uint64, ret uint64) { ret = fneg64(f) }`
494			`func f32to64c(f uint32, ret uint64) { ret = f32to64(f) }`
495			`func f64to32c(f uint64, ret uint32) { ret = f64to32(f) }`
496			`func fcmp64c(f, g uint64, ret int, retnan bool) { ret, retnan = fcmp64(f, g) }`
497			`func fintto64c(val int64, ret uint64) { ret = fintto64(val) }`
498			`func f64tointc(f uint64, ret int64, retok bool) { ret, retok = f64toint(f) }`