1// Copyright 2009 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
5package strconv_test
6
7import (
8	"bufio"
9	"fmt"
10	"io"
11	"os"
12	"strconv"
13	"strings"
14	"testing"
15)
16
17func pow2(i int) float64 {
18	switch {
19	case i < 0:
20		return 1 / pow2(-i)
21	case i == 0:
22		return 1
23	case i == 1:
24		return 2
25	}
26	return pow2(i/2) * pow2(i-i/2)
27}
28
29// Wrapper around strconv.ParseFloat(x, 64).  Handles dddddp+ddd (binary exponent)
30// itself, passes the rest on to strconv.ParseFloat.
31func myatof64(s string) (f float64, ok bool) {
32	a := strings.SplitN(s, "p", 2)
33	if len(a) == 2 {
34		n, err := strconv.ParseInt(a[0], 10, 64)
35		if err != nil {
36			return 0, false
37		}
38		e, err1 := strconv.Atoi(a[1])
39		if err1 != nil {
40			println("bad e", a[1])
41			return 0, false
42		}
43		v := float64(n)
44		// We expect that v*pow2(e) fits in a float64,
45		// but pow2(e) by itself may not.  Be careful.
46		if e <= -1000 {
47			v *= pow2(-1000)
48			e += 1000
49			for e < 0 {
50				v /= 2
51				e++
52			}
53			return v, true
54		}
55		if e >= 1000 {
56			v *= pow2(1000)
57			e -= 1000
58			for e > 0 {
59				v *= 2
60				e--
61			}
62			return v, true
63		}
64		return v * pow2(e), true
65	}
66	f1, err := strconv.ParseFloat(s, 64)
67	if err != nil {
68		return 0, false
69	}
70	return f1, true
71}
72
73// Wrapper around strconv.ParseFloat(x, 32).  Handles dddddp+ddd (binary exponent)
74// itself, passes the rest on to strconv.ParseFloat.
75func myatof32(s string) (f float32, ok bool) {
76	a := strings.SplitN(s, "p", 2)
77	if len(a) == 2 {
78		n, err := strconv.Atoi(a[0])
79		if err != nil {
80			println("bad n", a[0])
81			return 0, false
82		}
83		e, err1 := strconv.Atoi(a[1])
84		if err1 != nil {
85			println("bad p", a[1])
86			return 0, false
87		}
88		return float32(float64(n) * pow2(e)), true
89	}
90	f64, err1 := strconv.ParseFloat(s, 32)
91	f1 := float32(f64)
92	if err1 != nil {
93		return 0, false
94	}
95	return f1, true
96}
97
98func TestFp(t *testing.T) {
99	f, err := os.Open("testdata/testfp.txt")
100	if err != nil {
101		t.Fatal("testfp: open testdata/testfp.txt:", err)
102	}
103	defer f.Close()
104
105	b := bufio.NewReader(f)
106
107	lineno := 0
108	for {
109		line, err2 := b.ReadString('\n')
110		if err2 == io.EOF {
111			break
112		}
113		if err2 != nil {
114			t.Fatal("testfp: read testdata/testfp.txt: " + err2.Error())
115		}
116		line = line[0 : len(line)-1]
117		lineno++
118		if len(line) == 0 || line[0] == '#' {
119			continue
120		}
121		a := strings.Split(line, " ")
122		if len(a) != 4 {
123			t.Error("testdata/testfp.txt:", lineno, ": wrong field count")
124			continue
125		}
126		var s string
127		var v float64
128		switch a[0] {
129		case "float64":
130			var ok bool
131			v, ok = myatof64(a[2])
132			if !ok {
133				t.Error("testdata/testfp.txt:", lineno, ": cannot atof64 ", a[2])
134				continue
135			}
136			s = fmt.Sprintf(a[1], v)
137		case "float32":
138			v1, ok := myatof32(a[2])
139			if !ok {
140				t.Error("testdata/testfp.txt:", lineno, ": cannot atof32 ", a[2])
141				continue
142			}
143			s = fmt.Sprintf(a[1], v1)
144			v = float64(v1)
145		}
146		if s != a[3] {
147			t.Error("testdata/testfp.txt:", lineno, ": ", a[0], " ", a[1], " ", a[2], " (", v, ") ",
148				"want ", a[3], " got ", s)
149		}
150	}
151}
152