From ba5426b812cc6a5a2428c61e9f94db159dc1e706 Mon Sep 17 00:00:00 2001
From: Karl Gaissmaier <karl.gaissmaier@uni-ulm.de>
Date: Wed, 28 Aug 2024 13:18:35 +0200
Subject: [PATCH] internal renaming

---
 conversion.go      | 24 ++++++++++++------------
 conversion_test.go | 13 -------------
 uint128.go         | 24 ++++++++++++------------
 3 files changed, 24 insertions(+), 37 deletions(-)

diff --git a/conversion.go b/conversion.go
index a09428d..23d2e0d 100644
--- a/conversion.go
+++ b/conversion.go
@@ -11,25 +11,25 @@ type addr struct {
 	is4 bool
 }
 
-func peek(a netip.Addr) (b addr) {
+func peek(a netip.Addr) addr {
+	var b addr
 	b.is4 = a.Is4()
 
-	raw := a.As16()
-	b.ip.hi = binary.BigEndian.Uint64(raw[:8])
-	b.ip.lo = binary.BigEndian.Uint64(raw[8:])
-	return
+	a16 := a.As16()
+	b.ip.hi = binary.BigEndian.Uint64(a16[:8])
+	b.ip.lo = binary.BigEndian.Uint64(a16[8:])
+	return b
 }
 
 func back(a addr) netip.Addr {
-	var a6 [16]byte
-	binary.BigEndian.PutUint64(a6[:8], a.ip.hi)
-	binary.BigEndian.PutUint64(a6[8:], a.ip.lo)
+	var a16 [16]byte
+	binary.BigEndian.PutUint64(a16[:8], a.ip.hi)
+	binary.BigEndian.PutUint64(a16[8:], a.ip.lo)
 
 	if a.is4 {
-		// convert slice to array pointer
-		a4 := (*[4]byte)(a6[12:])
-		return netip.AddrFrom4(*a4)
+		// slice it and convert it back to array on the fly
+		return netip.AddrFrom4(*(*[4]byte)(a16[12:]))
 	}
 
-	return netip.AddrFrom16(a6)
+	return netip.AddrFrom16(a16)
 }
diff --git a/conversion_test.go b/conversion_test.go
index 34bc89e..f07d875 100644
--- a/conversion_test.go
+++ b/conversion_test.go
@@ -3,23 +3,10 @@ package extnetip
 import (
 	"net/netip"
 	"testing"
-	"unsafe"
 )
 
 var mustAddr = netip.MustParseAddr
 
-// is it still safe to use unsafe to peek into the internal netip.Addr representation?
-func TestSizeof(t *testing.T) {
-	s1 := unsafe.Sizeof(addr{})
-	s2 := unsafe.Sizeof(netip.Addr{})
-
-	if s1 != s2 {
-		t.Fatalf(
-			"Address representations differ in size, (%v != %v), maybe internal representation for netip.Addr has changed.",
-			s1, s2)
-	}
-}
-
 func TestIdempotent(t *testing.T) {
 	t.Parallel()
 	v4 := mustAddr("0.0.0.0")
diff --git a/uint128.go b/uint128.go
index 96c66e8..92a4f8e 100644
--- a/uint128.go
+++ b/uint128.go
@@ -9,16 +9,16 @@ type uint128 struct {
 	lo uint64
 }
 
-func (u uint128) and(m uint128) uint128 {
-	return uint128{u.hi & m.hi, u.lo & m.lo}
+func (u uint128) and(v uint128) uint128 {
+	return uint128{u.hi & v.hi, u.lo & v.lo}
 }
 
-func (u uint128) or(m uint128) uint128 {
-	return uint128{u.hi | m.hi, u.lo | m.lo}
+func (u uint128) or(v uint128) uint128 {
+	return uint128{u.hi | v.hi, u.lo | v.lo}
 }
 
-func (u uint128) xor(m uint128) uint128 {
-	return uint128{u.hi ^ m.hi, u.lo ^ m.lo}
+func (u uint128) xor(v uint128) uint128 {
+	return uint128{u.hi ^ v.hi, u.lo ^ v.lo}
 }
 
 func (u uint128) not() uint128 {
@@ -29,8 +29,8 @@ func mask6(n int) uint128 {
 	return uint128{^(^uint64(0) >> n), ^uint64(0) << (128 - n)}
 }
 
-func u64CommonPrefixLen(a, b uint64) int {
-	return bits.LeadingZeros64(a ^ b)
+func u64CommonPrefixLen(u, v uint64) int {
+	return bits.LeadingZeros64(u ^ v)
 }
 
 func (u uint128) commonPrefixLen(v uint128) (n int) {
@@ -41,16 +41,16 @@ func (u uint128) commonPrefixLen(v uint128) (n int) {
 }
 
 // prefixOK returns the common bits of two uint128 and true if they present exactly a prefix.
-func (a uint128) prefixOK(b uint128) (bits int, ok bool) {
-	bits = a.commonPrefixLen(b)
+func (u uint128) prefixOK(v uint128) (bits int, ok bool) {
+	bits = u.commonPrefixLen(v)
 	if bits == 128 {
 		return bits, true
 	}
 	mask := mask6(bits)
 
 	// check if mask applied to first and last results in all zeros and all ones
-	allZero := a.xor(a.and(mask)) == uint128{}
-	allOnes := b.or(mask) == uint128{^uint64(0), ^uint64(0)}
+	allZero := u.xor(u.and(mask)) == uint128{}
+	allOnes := v.or(mask) == uint128{^uint64(0), ^uint64(0)}
 
 	return bits, allZero && allOnes
 }