From: Jes Cok <xigua67damn@gmail.com>
Date: Thu, 7 Sep 2023 11:07:30 +0000 (+0000)
Subject: all: calculate the median uniformly
X-Git-Tag: go1.22rc1~915
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=267323ef2d22da4b2a5ed1ed6f220421aa580a6c;p=gostls13.git

all: calculate the median uniformly

Like sort.Search, use "h := int(uint(i+j) >> 1)" style code to calculate
the median.

Change-Id: Ifb1a19dde1c6ed6c1654bc642fc9565a8b6c5fc4
GitHub-Last-Rev: e2213b738832f1674948d6507f40e2c0b98cb972
GitHub-Pull-Request: golang/go#62503
Reviewed-on: https://go-review.googlesource.com/c/go/+/526496
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
---

diff --git a/src/regexp/syntax/prog.go b/src/regexp/syntax/prog.go
index 66995e2052..d69ae1a12d 100644
--- a/src/regexp/syntax/prog.go
+++ b/src/regexp/syntax/prog.go
@@ -247,7 +247,7 @@ func (i *Inst) MatchRunePos(r rune) int {
 	lo := 0
 	hi := len(rune) / 2
 	for lo < hi {
-		m := lo + (hi-lo)/2
+		m := int(uint(lo+hi) >> 1)
 		if c := rune[2*m]; c <= r {
 			if r <= rune[2*m+1] {
 				return m
diff --git a/src/time/zoneinfo.go b/src/time/zoneinfo.go
index 4edcf3d98f..42d40d584e 100644
--- a/src/time/zoneinfo.go
+++ b/src/time/zoneinfo.go
@@ -184,7 +184,7 @@ func (l *Location) lookup(sec int64) (name string, offset int, start, end int64,
 	lo := 0
 	hi := len(tx)
 	for hi-lo > 1 {
-		m := lo + (hi-lo)/2
+		m := int(uint(lo+hi) >> 1)
 		lim := tx[m].when
 		if sec < lim {
 			end = lim
diff --git a/src/unicode/letter.go b/src/unicode/letter.go
index f3f8e52964..f64dfc9af5 100644
--- a/src/unicode/letter.go
+++ b/src/unicode/letter.go
@@ -106,7 +106,7 @@ func is16(ranges []Range16, r uint16) bool {
 	lo := 0
 	hi := len(ranges)
 	for lo < hi {
-		m := lo + (hi-lo)/2
+		m := int(uint(lo+hi) >> 1)
 		range_ := &ranges[m]
 		if range_.Lo <= r && r <= range_.Hi {
 			return range_.Stride == 1 || (r-range_.Lo)%range_.Stride == 0
@@ -139,7 +139,7 @@ func is32(ranges []Range32, r uint32) bool {
 	lo := 0
 	hi := len(ranges)
 	for lo < hi {
-		m := lo + (hi-lo)/2
+		m := int(uint(lo+hi) >> 1)
 		range_ := ranges[m]
 		if range_.Lo <= r && r <= range_.Hi {
 			return range_.Stride == 1 || (r-range_.Lo)%range_.Stride == 0
@@ -216,7 +216,7 @@ func to(_case int, r rune, caseRange []CaseRange) (mappedRune rune, foundMapping
 	lo := 0
 	hi := len(caseRange)
 	for lo < hi {
-		m := lo + (hi-lo)/2
+		m := int(uint(lo+hi) >> 1)
 		cr := caseRange[m]
 		if rune(cr.Lo) <= r && r <= rune(cr.Hi) {
 			delta := cr.Delta[_case]
@@ -350,7 +350,7 @@ func SimpleFold(r rune) rune {
 	lo := 0
 	hi := len(caseOrbit)
 	for lo < hi {
-		m := lo + (hi-lo)/2
+		m := int(uint(lo+hi) >> 1)
 		if rune(caseOrbit[m].From) < r {
 			lo = m + 1
 		} else {
diff --git a/src/unicode/letter_test.go b/src/unicode/letter_test.go
index a91e3a326f..123f9a642e 100644
--- a/src/unicode/letter_test.go
+++ b/src/unicode/letter_test.go
@@ -518,7 +518,7 @@ func binary(ranges []Range16, r uint16) bool {
 	lo := 0
 	hi := len(ranges)
 	for lo < hi {
-		m := lo + (hi-lo)/2
+		m := int(uint(lo+hi) >> 1)
 		range_ := &ranges[m]
 		if range_.Lo <= r && r <= range_.Hi {
 			return (r-range_.Lo)%range_.Stride == 0