1 files changed, 142 insertions, 0 deletions
diff --git a/src/strconv/fp_test.go b/src/strconv/fp_test.go
new file mode 100644
index 0000000..fd73958
--- /dev/null
+++ b/src/strconv/fp_test.go
@@ -0,0 +1,142 @@
+// 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) {
+	if mant, exp, ok := strings.Cut(s, "p"); ok {
+		n, err := strconv.ParseInt(mant, 10, 64)
+		if err != nil {
+			return 0, false
+		}
+		e, err1 := strconv.Atoi(exp)
+		if err1 != nil {
+			println("bad e", exp)
+			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) {
+	if mant, exp, ok := strings.Cut(s, "p"); ok {
+		n, err := strconv.Atoi(mant)
+		if err != nil {
+			println("bad n", mant)
+			return 0, false
+		}
+		e, err1 := strconv.Atoi(exp)
+		if err1 != nil {
+			println("bad p", exp)
+			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())
+	}
+}