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package jsoncolor
import "unsafe"
// asciiValid returns true if b contains only ASCII characters.
//
// From https://github.com/segmentio/encoding/blob/v0.1.14/ascii/valid.go#L28
//
//go:nosplit
func asciiValid(b []byte) bool {
s, n := unsafe.Pointer(&b), uintptr(len(b))
i := uintptr(0)
p := *(*unsafe.Pointer)(s)
for n >= 8 {
if ((*(*uint64)(unsafe.Pointer(uintptr(p) + i))) & 0x8080808080808080) != 0 {
return false
}
i += 8
n -= 8
}
if n >= 4 {
if ((*(*uint32)(unsafe.Pointer(uintptr(p) + i))) & 0x80808080) != 0 {
return false
}
i += 4
n -= 4
}
var x uint32
switch n {
case 3:
x = uint32(*(*uint8)(unsafe.Pointer(uintptr(p) + i))) | uint32(*(*uint16)(unsafe.Pointer(uintptr(p) + i + 1)))<<8
case 2:
x = uint32(*(*uint16)(unsafe.Pointer(uintptr(p) + i)))
case 1:
x = uint32(*(*uint8)(unsafe.Pointer(uintptr(p) + i)))
default:
return true
}
return (x & 0x80808080) == 0
}
// asciiValidPrint returns true if b contains only printable ASCII characters.
//
// From https://github.com/segmentio/encoding/blob/v0.1.14/ascii/valid.go#L83
//
//go:nosplit
func asciiValidPrint(b []byte) bool {
s, n := unsafe.Pointer(&b), uintptr(len(b))
if n == 0 {
return true
}
i := uintptr(0)
p := *(*unsafe.Pointer)(s)
for (n - i) >= 8 {
x := *(*uint64)(unsafe.Pointer(uintptr(p) + i))
if hasLess64(x, 0x20) || hasMore64(x, 0x7e) {
return false
}
i += 8
}
if (n - i) >= 4 {
x := *(*uint32)(unsafe.Pointer(uintptr(p) + i))
if hasLess32(x, 0x20) || hasMore32(x, 0x7e) {
return false
}
i += 4
}
var x uint32
switch n - i {
case 3:
x = 0x20000000 | uint32(*(*uint8)(unsafe.Pointer(uintptr(p) + i))) | uint32(*(*uint16)(unsafe.Pointer(uintptr(p) + i + 1)))<<8
case 2:
x = 0x20200000 | uint32(*(*uint16)(unsafe.Pointer(uintptr(p) + i)))
case 1:
x = 0x20202000 | uint32(*(*uint8)(unsafe.Pointer(uintptr(p) + i)))
default:
return true
}
return !(hasLess32(x, 0x20) || hasMore32(x, 0x7e))
}
// https://graphics.stanford.edu/~seander/bithacks.html#HasLessInWord
const (
hasLessConstL64 = (^uint64(0)) / 255
hasLessConstR64 = hasLessConstL64 * 128
hasLessConstL32 = (^uint32(0)) / 255
hasLessConstR32 = hasLessConstL32 * 128
hasMoreConstL64 = (^uint64(0)) / 255
hasMoreConstR64 = hasMoreConstL64 * 128
hasMoreConstL32 = (^uint32(0)) / 255
hasMoreConstR32 = hasMoreConstL32 * 128
)
//go:nosplit
func hasLess64(x, n uint64) bool {
return ((x - (hasLessConstL64 * n)) & ^x & hasLessConstR64) != 0
}
//go:nosplit
func hasLess32(x, n uint32) bool {
return ((x - (hasLessConstL32 * n)) & ^x & hasLessConstR32) != 0
}
//go:nosplit
func hasMore64(x, n uint64) bool {
return (((x + (hasMoreConstL64 * (127 - n))) | x) & hasMoreConstR64) != 0
}
//go:nosplit
func hasMore32(x, n uint32) bool {
return (((x + (hasMoreConstL32 * (127 - n))) | x) & hasMoreConstR32) != 0
}
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