1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
|
// Copyright 2009 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.
package strconv_test
import (
"bufio"
"fmt"
"os"
"strconv"
"strings"
"testing"
)
func pow2(i int) float64 {
switch {
case i < 0:
return 1 / pow2(-i)
case i == 0:
return 1
case i == 1:
return 2
}
return pow2(i/2) * pow2(i-i/2)
}
// Wrapper around strconv.ParseFloat(x, 64). Handles dddddp+ddd (binary exponent)
// itself, passes the rest on to strconv.ParseFloat.
func myatof64(s string) (f float64, ok bool) {
a := strings.SplitN(s, "p", 2)
if len(a) == 2 {
n, err := strconv.ParseInt(a[0], 10, 64)
if err != nil {
return 0, false
}
e, err1 := strconv.Atoi(a[1])
if err1 != nil {
println("bad e", a[1])
return 0, false
}
v := float64(n)
// We expect that v*pow2(e) fits in a float64,
// but pow2(e) by itself may not. Be careful.
if e <= -1000 {
v *= pow2(-1000)
e += 1000
for e < 0 {
v /= 2
e++
}
return v, true
}
if e >= 1000 {
v *= pow2(1000)
e -= 1000
for e > 0 {
v *= 2
e--
}
return v, true
}
return v * pow2(e), true
}
f1, err := strconv.ParseFloat(s, 64)
if err != nil {
return 0, false
}
return f1, true
}
// Wrapper around strconv.ParseFloat(x, 32). Handles dddddp+ddd (binary exponent)
// itself, passes the rest on to strconv.ParseFloat.
func myatof32(s string) (f float32, ok bool) {
a := strings.SplitN(s, "p", 2)
if len(a) == 2 {
n, err := strconv.Atoi(a[0])
if err != nil {
println("bad n", a[0])
return 0, false
}
e, err1 := strconv.Atoi(a[1])
if err1 != nil {
println("bad p", a[1])
return 0, false
}
return float32(float64(n) * pow2(e)), true
}
f64, err1 := strconv.ParseFloat(s, 32)
f1 := float32(f64)
if err1 != nil {
return 0, false
}
return f1, true
}
func TestFp(t *testing.T) {
f, err := os.Open("testdata/testfp.txt")
if err != nil {
t.Fatal("testfp: open testdata/testfp.txt:", err)
}
defer f.Close()
s := bufio.NewScanner(f)
for lineno := 1; s.Scan(); lineno++ {
line := s.Text()
if len(line) == 0 || line[0] == '#' {
continue
}
a := strings.Split(line, " ")
if len(a) != 4 {
t.Error("testdata/testfp.txt:", lineno, ": wrong field count")
continue
}
var s string
var v float64
switch a[0] {
case "float64":
var ok bool
v, ok = myatof64(a[2])
if !ok {
t.Error("testdata/testfp.txt:", lineno, ": cannot atof64 ", a[2])
continue
}
s = fmt.Sprintf(a[1], v)
case "float32":
v1, ok := myatof32(a[2])
if !ok {
t.Error("testdata/testfp.txt:", lineno, ": cannot atof32 ", a[2])
continue
}
s = fmt.Sprintf(a[1], v1)
v = float64(v1)
}
if s != a[3] {
t.Error("testdata/testfp.txt:", lineno, ": ", a[0], " ", a[1], " ", a[2], " (", v, ") ",
"want ", a[3], " got ", s)
}
}
if s.Err() != nil {
t.Fatal("testfp: read testdata/testfp.txt: ", s.Err())
}
}
|
