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//go:build purego || !amd64
// +build purego !amd64
package ascii
// EqualFoldString is a version of strings.EqualFold designed to work on ASCII
// input instead of UTF-8.
//
// When the program has guarantees that the input is composed of ASCII
// characters only, it allows for greater optimizations.
func EqualFoldString(a, b string) bool {
if len(a) != len(b) {
return false
}
var cmp byte
for len(a) >= 8 {
cmp |= lowerCase[a[0]] ^ lowerCase[b[0]]
cmp |= lowerCase[a[1]] ^ lowerCase[b[1]]
cmp |= lowerCase[a[2]] ^ lowerCase[b[2]]
cmp |= lowerCase[a[3]] ^ lowerCase[b[3]]
cmp |= lowerCase[a[4]] ^ lowerCase[b[4]]
cmp |= lowerCase[a[5]] ^ lowerCase[b[5]]
cmp |= lowerCase[a[6]] ^ lowerCase[b[6]]
cmp |= lowerCase[a[7]] ^ lowerCase[b[7]]
if cmp != 0 {
return false
}
a = a[8:]
b = b[8:]
}
switch len(a) {
case 7:
cmp |= lowerCase[a[6]] ^ lowerCase[b[6]]
fallthrough
case 6:
cmp |= lowerCase[a[5]] ^ lowerCase[b[5]]
fallthrough
case 5:
cmp |= lowerCase[a[4]] ^ lowerCase[b[4]]
fallthrough
case 4:
cmp |= lowerCase[a[3]] ^ lowerCase[b[3]]
fallthrough
case 3:
cmp |= lowerCase[a[2]] ^ lowerCase[b[2]]
fallthrough
case 2:
cmp |= lowerCase[a[1]] ^ lowerCase[b[1]]
fallthrough
case 1:
cmp |= lowerCase[a[0]] ^ lowerCase[b[0]]
}
return cmp == 0
}
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