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math/fixed: have Floor, Round and Ceil return int, not Int26_6.

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Change-Id: I1714bfbaf355771fb5d01508ac1dfe11c3db927a
Reviewed-on: https://go-review.googlesource.com/21787
Reviewed-by: Rob Pike <r@golang.org>
This commit is contained in:
Nigel Tao 2016-04-10 13:59:37 +10:00
parent 0991244d9d
commit c4e9f1b429
2 changed files with 111 additions and 30 deletions
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24
math/fixed/fixed.go
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@ -42,13 +42,19 @@ func (x Int26_6) String() string {
}
// Floor returns the greatest integer value less than or equal to x.
func (x Int26_6) Floor() Int26_6 { return (x + 0x00) &^ 0x3f }
//
// Its return type is int, not Int26_6.
func (x Int26_6) Floor() int { return int((x + 0x00) >> 6) }
// Round returns the nearest integer value to x. Ties are rounded up.
func (x Int26_6) Round() Int26_6 { return (x + 0x20) &^ 0x3f }
//
// Its return type is int, not Int26_6.
func (x Int26_6) Round() int { return int((x + 0x20) >> 6) }
// Ceil returns the least integer value greater than or equal to x.
func (x Int26_6) Ceil() Int26_6 { return (x + 0x3f) &^ 0x3f }
//
// Its return type is int, not Int26_6.
func (x Int26_6) Ceil() int { return int((x + 0x3f) >> 6) }
// Int52_12 is a signed 52.12 fixed-point number.
//
@ -75,13 +81,19 @@ func (x Int52_12) String() string {
}
// Floor returns the greatest integer value less than or equal to x.
func (x Int52_12) Floor() Int52_12 { return (x + 0x000) &^ 0xfff }
//
// Its return type is int, not Int52_12.
func (x Int52_12) Floor() int { return int((x + 0x000) >> 12) }
// Round returns the nearest integer value to x. Ties are rounded up.
func (x Int52_12) Round() Int52_12 { return (x + 0x800) &^ 0xfff }
//
// Its return type is int, not Int52_12.
func (x Int52_12) Round() int { return int((x + 0x800) >> 12) }
// Ceil returns the least integer value greater than or equal to x.
func (x Int52_12) Ceil() Int52_12 { return (x + 0xfff) &^ 0xfff }
//
// Its return type is int, not Int52_12.
func (x Int52_12) Ceil() int { return int((x + 0xfff) >> 12) }
// P returns the integer values x and y as a Point26_6.
//

105
math/fixed/fixed_test.go
View File

@ -8,34 +8,103 @@ import (
"testing"
)
var testCases = []struct {
x float64
s26_6 string
s52_12 string
floor int
round int
ceil int
}{{
x: 0,
s26_6: "0:00",
s52_12: "0:0000",
floor: 0,
round: 0,
ceil: 0,
}, {
x: 1,
s26_6: "1:00",
s52_12: "1:0000",
floor: 1,
round: 1,
ceil: 1,
}, {
x: 1.25,
s26_6: "1:16",
s52_12: "1:1024",
floor: 1,
round: 1,
ceil: 2,
}, {
x: 2.5,
s26_6: "2:32",
s52_12: "2:2048",
floor: 2,
round: 3,
ceil: 3,
}, {
x: 63 / 64.0,
s26_6: "0:63",
s52_12: "0:4032",
floor: 0,
round: 1,
ceil: 1,
}, {
x: -0.5,
s26_6: "-0:32",
s52_12: "-0:2048",
floor: -1,
round: +0,
ceil: +0,
}, {
x: -4.125,
s26_6: "-4:08",
s52_12: "-4:0512",
floor: -5,
round: -4,
ceil: -4,
}, {
x: -7.75,
s26_6: "-7:48",
s52_12: "-7:3072",
floor: -8,
round: -8,
ceil: -7,
}}
func TestInt26_6(t *testing.T) {
x := Int26_6(1<<6 + 1<<4)
if got, want := x.String(), "1:16"; got != want {
t.Errorf("String: got %q, want %q", got, want)
for _, tc := range testCases {
x := Int26_6(tc.x * (1 << 6))
if got, want := x.String(), tc.s26_6; got != want {
t.Errorf("tc.x=%v: String: got %q, want %q", tc.x, got, want)
}
if got, want := x.Floor(), Int26_6(1<<6); got != want {
t.Errorf("Floor: got %v, want %v", got, want)
if got, want := x.Floor(), tc.floor; got != want {
t.Errorf("tc.x=%v: Floor: got %v, want %v", tc.x, got, want)
}
if got, want := x.Round(), Int26_6(1<<6); got != want {
t.Errorf("Round: got %v, want %v", got, want)
if got, want := x.Round(), tc.round; got != want {
t.Errorf("tc.x=%v: Round: got %v, want %v", tc.x, got, want)
}
if got, want := x.Ceil(), tc.ceil; got != want {
t.Errorf("tc.x=%v: Ceil: got %v, want %v", tc.x, got, want)
}
if got, want := x.Ceil(), Int26_6(2<<6); got != want {
t.Errorf("Ceil: got %v, want %v", got, want)
}
}
func TestInt52_12(t *testing.T) {
x := Int52_12(1<<12 + 1<<10)
if got, want := x.String(), "1:1024"; got != want {
t.Errorf("String: got %q, want %q", got, want)
for _, tc := range testCases {
x := Int52_12(tc.x * (1 << 12))
if got, want := x.String(), tc.s52_12; got != want {
t.Errorf("tc.x=%v: String: got %q, want %q", tc.x, got, want)
}
if got, want := x.Floor(), Int52_12(1<<12); got != want {
t.Errorf("Floor: got %v, want %v", got, want)
if got, want := x.Floor(), tc.floor; got != want {
t.Errorf("tc.x=%v: Floor: got %v, want %v", tc.x, got, want)
}
if got, want := x.Round(), Int52_12(1<<12); got != want {
t.Errorf("Round: got %v, want %v", got, want)
if got, want := x.Round(), tc.round; got != want {
t.Errorf("tc.x=%v: Round: got %v, want %v", tc.x, got, want)
}
if got, want := x.Ceil(), tc.ceil; got != want {
t.Errorf("tc.x=%v: Ceil: got %v, want %v", tc.x, got, want)
}
if got, want := x.Ceil(), Int52_12(2<<12); got != want {
t.Errorf("Ceil: got %v, want %v", got, want)
}
}