From 404aeae4545d2426c089a5f8d5e82dae56f5212b Mon Sep 17 00:00:00 2001
From: Rutger Broekhoff
Date: Fri, 29 Dec 2023 21:31:53 +0100
Subject: Make Nix builds work

---
 .../github.com/klauspost/compress/s2/encode_go.go  | 729 +++++++++++++++++++++
 1 file changed, 729 insertions(+)
 create mode 100644 vendor/github.com/klauspost/compress/s2/encode_go.go

(limited to 'vendor/github.com/klauspost/compress/s2/encode_go.go')

diff --git a/vendor/github.com/klauspost/compress/s2/encode_go.go b/vendor/github.com/klauspost/compress/s2/encode_go.go
new file mode 100644
index 0000000..6b393c3
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/s2/encode_go.go
@@ -0,0 +1,729 @@
+//go:build !amd64 || appengine || !gc || noasm
+// +build !amd64 appengine !gc noasm
+
+package s2
+
+import (
+	"bytes"
+	"math/bits"
+)
+
+const hasAmd64Asm = false
+
+// encodeBlock encodes a non-empty src to a guaranteed-large-enough dst. It
+// assumes that the varint-encoded length of the decompressed bytes has already
+// been written.
+//
+// It also assumes that:
+//
+//	len(dst) >= MaxEncodedLen(len(src))
+func encodeBlock(dst, src []byte) (d int) {
+	if len(src) < minNonLiteralBlockSize {
+		return 0
+	}
+	return encodeBlockGo(dst, src)
+}
+
+// encodeBlockBetter encodes a non-empty src to a guaranteed-large-enough dst. It
+// assumes that the varint-encoded length of the decompressed bytes has already
+// been written.
+//
+// It also assumes that:
+//
+//	len(dst) >= MaxEncodedLen(len(src))
+func encodeBlockBetter(dst, src []byte) (d int) {
+	return encodeBlockBetterGo(dst, src)
+}
+
+// encodeBlockBetter encodes a non-empty src to a guaranteed-large-enough dst. It
+// assumes that the varint-encoded length of the decompressed bytes has already
+// been written.
+//
+// It also assumes that:
+//
+//	len(dst) >= MaxEncodedLen(len(src))
+func encodeBlockBetterSnappy(dst, src []byte) (d int) {
+	return encodeBlockBetterSnappyGo(dst, src)
+}
+
+// encodeBlock encodes a non-empty src to a guaranteed-large-enough dst. It
+// assumes that the varint-encoded length of the decompressed bytes has already
+// been written.
+//
+// It also assumes that:
+//
+//	len(dst) >= MaxEncodedLen(len(src))
+func encodeBlockSnappy(dst, src []byte) (d int) {
+	if len(src) < minNonLiteralBlockSize {
+		return 0
+	}
+	return encodeBlockSnappyGo(dst, src)
+}
+
+// emitLiteral writes a literal chunk and returns the number of bytes written.
+//
+// It assumes that:
+//
+//	dst is long enough to hold the encoded bytes
+//	0 <= len(lit) && len(lit) <= math.MaxUint32
+func emitLiteral(dst, lit []byte) int {
+	if len(lit) == 0 {
+		return 0
+	}
+	const num = 63<<2 | tagLiteral
+	i, n := 0, uint(len(lit)-1)
+	switch {
+	case n < 60:
+		dst[0] = uint8(n)<<2 | tagLiteral
+		i = 1
+	case n < 1<<8:
+		dst[1] = uint8(n)
+		dst[0] = 60<<2 | tagLiteral
+		i = 2
+	case n < 1<<16:
+		dst[2] = uint8(n >> 8)
+		dst[1] = uint8(n)
+		dst[0] = 61<<2 | tagLiteral
+		i = 3
+	case n < 1<<24:
+		dst[3] = uint8(n >> 16)
+		dst[2] = uint8(n >> 8)
+		dst[1] = uint8(n)
+		dst[0] = 62<<2 | tagLiteral
+		i = 4
+	default:
+		dst[4] = uint8(n >> 24)
+		dst[3] = uint8(n >> 16)
+		dst[2] = uint8(n >> 8)
+		dst[1] = uint8(n)
+		dst[0] = 63<<2 | tagLiteral
+		i = 5
+	}
+	return i + copy(dst[i:], lit)
+}
+
+// emitRepeat writes a repeat chunk and returns the number of bytes written.
+// Length must be at least 4 and < 1<<24
+func emitRepeat(dst []byte, offset, length int) int {
+	// Repeat offset, make length cheaper
+	length -= 4
+	if length <= 4 {
+		dst[0] = uint8(length)<<2 | tagCopy1
+		dst[1] = 0
+		return 2
+	}
+	if length < 8 && offset < 2048 {
+		// Encode WITH offset
+		dst[1] = uint8(offset)
+		dst[0] = uint8(offset>>8)<<5 | uint8(length)<<2 | tagCopy1
+		return 2
+	}
+	if length < (1<<8)+4 {
+		length -= 4
+		dst[2] = uint8(length)
+		dst[1] = 0
+		dst[0] = 5<<2 | tagCopy1
+		return 3
+	}
+	if length < (1<<16)+(1<<8) {
+		length -= 1 << 8
+		dst[3] = uint8(length >> 8)
+		dst[2] = uint8(length >> 0)
+		dst[1] = 0
+		dst[0] = 6<<2 | tagCopy1
+		return 4
+	}
+	const maxRepeat = (1 << 24) - 1
+	length -= 1 << 16
+	left := 0
+	if length > maxRepeat {
+		left = length - maxRepeat + 4
+		length = maxRepeat - 4
+	}
+	dst[4] = uint8(length >> 16)
+	dst[3] = uint8(length >> 8)
+	dst[2] = uint8(length >> 0)
+	dst[1] = 0
+	dst[0] = 7<<2 | tagCopy1
+	if left > 0 {
+		return 5 + emitRepeat(dst[5:], offset, left)
+	}
+	return 5
+}
+
+// emitCopy writes a copy chunk and returns the number of bytes written.
+//
+// It assumes that:
+//
+//	dst is long enough to hold the encoded bytes
+//	1 <= offset && offset <= math.MaxUint32
+//	4 <= length && length <= 1 << 24
+func emitCopy(dst []byte, offset, length int) int {
+	if offset >= 65536 {
+		i := 0
+		if length > 64 {
+			// Emit a length 64 copy, encoded as 5 bytes.
+			dst[4] = uint8(offset >> 24)
+			dst[3] = uint8(offset >> 16)
+			dst[2] = uint8(offset >> 8)
+			dst[1] = uint8(offset)
+			dst[0] = 63<<2 | tagCopy4
+			length -= 64
+			if length >= 4 {
+				// Emit remaining as repeats
+				return 5 + emitRepeat(dst[5:], offset, length)
+			}
+			i = 5
+		}
+		if length == 0 {
+			return i
+		}
+		// Emit a copy, offset encoded as 4 bytes.
+		dst[i+0] = uint8(length-1)<<2 | tagCopy4
+		dst[i+1] = uint8(offset)
+		dst[i+2] = uint8(offset >> 8)
+		dst[i+3] = uint8(offset >> 16)
+		dst[i+4] = uint8(offset >> 24)
+		return i + 5
+	}
+
+	// Offset no more than 2 bytes.
+	if length > 64 {
+		off := 3
+		if offset < 2048 {
+			// emit 8 bytes as tagCopy1, rest as repeats.
+			dst[1] = uint8(offset)
+			dst[0] = uint8(offset>>8)<<5 | uint8(8-4)<<2 | tagCopy1
+			length -= 8
+			off = 2
+		} else {
+			// Emit a length 60 copy, encoded as 3 bytes.
+			// Emit remaining as repeat value (minimum 4 bytes).
+			dst[2] = uint8(offset >> 8)
+			dst[1] = uint8(offset)
+			dst[0] = 59<<2 | tagCopy2
+			length -= 60
+		}
+		// Emit remaining as repeats, at least 4 bytes remain.
+		return off + emitRepeat(dst[off:], offset, length)
+	}
+	if length >= 12 || offset >= 2048 {
+		// Emit the remaining copy, encoded as 3 bytes.
+		dst[2] = uint8(offset >> 8)
+		dst[1] = uint8(offset)
+		dst[0] = uint8(length-1)<<2 | tagCopy2
+		return 3
+	}
+	// Emit the remaining copy, encoded as 2 bytes.
+	dst[1] = uint8(offset)
+	dst[0] = uint8(offset>>8)<<5 | uint8(length-4)<<2 | tagCopy1
+	return 2
+}
+
+// emitCopyNoRepeat writes a copy chunk and returns the number of bytes written.
+//
+// It assumes that:
+//
+//	dst is long enough to hold the encoded bytes
+//	1 <= offset && offset <= math.MaxUint32
+//	4 <= length && length <= 1 << 24
+func emitCopyNoRepeat(dst []byte, offset, length int) int {
+	if offset >= 65536 {
+		i := 0
+		if length > 64 {
+			// Emit a length 64 copy, encoded as 5 bytes.
+			dst[4] = uint8(offset >> 24)
+			dst[3] = uint8(offset >> 16)
+			dst[2] = uint8(offset >> 8)
+			dst[1] = uint8(offset)
+			dst[0] = 63<<2 | tagCopy4
+			length -= 64
+			if length >= 4 {
+				// Emit remaining as repeats
+				return 5 + emitCopyNoRepeat(dst[5:], offset, length)
+			}
+			i = 5
+		}
+		if length == 0 {
+			return i
+		}
+		// Emit a copy, offset encoded as 4 bytes.
+		dst[i+0] = uint8(length-1)<<2 | tagCopy4
+		dst[i+1] = uint8(offset)
+		dst[i+2] = uint8(offset >> 8)
+		dst[i+3] = uint8(offset >> 16)
+		dst[i+4] = uint8(offset >> 24)
+		return i + 5
+	}
+
+	// Offset no more than 2 bytes.
+	if length > 64 {
+		// Emit a length 60 copy, encoded as 3 bytes.
+		// Emit remaining as repeat value (minimum 4 bytes).
+		dst[2] = uint8(offset >> 8)
+		dst[1] = uint8(offset)
+		dst[0] = 59<<2 | tagCopy2
+		length -= 60
+		// Emit remaining as repeats, at least 4 bytes remain.
+		return 3 + emitCopyNoRepeat(dst[3:], offset, length)
+	}
+	if length >= 12 || offset >= 2048 {
+		// Emit the remaining copy, encoded as 3 bytes.
+		dst[2] = uint8(offset >> 8)
+		dst[1] = uint8(offset)
+		dst[0] = uint8(length-1)<<2 | tagCopy2
+		return 3
+	}
+	// Emit the remaining copy, encoded as 2 bytes.
+	dst[1] = uint8(offset)
+	dst[0] = uint8(offset>>8)<<5 | uint8(length-4)<<2 | tagCopy1
+	return 2
+}
+
+// matchLen returns how many bytes match in a and b
+//
+// It assumes that:
+//
+//	len(a) <= len(b)
+func matchLen(a []byte, b []byte) int {
+	b = b[:len(a)]
+	var checked int
+	if len(a) > 4 {
+		// Try 4 bytes first
+		if diff := load32(a, 0) ^ load32(b, 0); diff != 0 {
+			return bits.TrailingZeros32(diff) >> 3
+		}
+		// Switch to 8 byte matching.
+		checked = 4
+		a = a[4:]
+		b = b[4:]
+		for len(a) >= 8 {
+			b = b[:len(a)]
+			if diff := load64(a, 0) ^ load64(b, 0); diff != 0 {
+				return checked + (bits.TrailingZeros64(diff) >> 3)
+			}
+			checked += 8
+			a = a[8:]
+			b = b[8:]
+		}
+	}
+	b = b[:len(a)]
+	for i := range a {
+		if a[i] != b[i] {
+			return int(i) + checked
+		}
+	}
+	return len(a) + checked
+}
+
+// input must be > inputMargin
+func calcBlockSize(src []byte) (d int) {
+	// Initialize the hash table.
+	const (
+		tableBits    = 13
+		maxTableSize = 1 << tableBits
+	)
+
+	var table [maxTableSize]uint32
+
+	// sLimit is when to stop looking for offset/length copies. The inputMargin
+	// lets us use a fast path for emitLiteral in the main loop, while we are
+	// looking for copies.
+	sLimit := len(src) - inputMargin
+
+	// Bail if we can't compress to at least this.
+	dstLimit := len(src) - len(src)>>5 - 5
+
+	// nextEmit is where in src the next emitLiteral should start from.
+	nextEmit := 0
+
+	// The encoded form must start with a literal, as there are no previous
+	// bytes to copy, so we start looking for hash matches at s == 1.
+	s := 1
+	cv := load64(src, s)
+
+	// We search for a repeat at -1, but don't output repeats when nextEmit == 0
+	repeat := 1
+
+	for {
+		candidate := 0
+		for {
+			// Next src position to check
+			nextS := s + (s-nextEmit)>>6 + 4
+			if nextS > sLimit {
+				goto emitRemainder
+			}
+			hash0 := hash6(cv, tableBits)
+			hash1 := hash6(cv>>8, tableBits)
+			candidate = int(table[hash0])
+			candidate2 := int(table[hash1])
+			table[hash0] = uint32(s)
+			table[hash1] = uint32(s + 1)
+			hash2 := hash6(cv>>16, tableBits)
+
+			// Check repeat at offset checkRep.
+			const checkRep = 1
+			if uint32(cv>>(checkRep*8)) == load32(src, s-repeat+checkRep) {
+				base := s + checkRep
+				// Extend back
+				for i := base - repeat; base > nextEmit && i > 0 && src[i-1] == src[base-1]; {
+					i--
+					base--
+				}
+				d += emitLiteralSize(src[nextEmit:base])
+
+				// Extend forward
+				candidate := s - repeat + 4 + checkRep
+				s += 4 + checkRep
+				for s <= sLimit {
+					if diff := load64(src, s) ^ load64(src, candidate); diff != 0 {
+						s += bits.TrailingZeros64(diff) >> 3
+						break
+					}
+					s += 8
+					candidate += 8
+				}
+
+				d += emitCopyNoRepeatSize(repeat, s-base)
+				nextEmit = s
+				if s >= sLimit {
+					goto emitRemainder
+				}
+
+				cv = load64(src, s)
+				continue
+			}
+
+			if uint32(cv) == load32(src, candidate) {
+				break
+			}
+			candidate = int(table[hash2])
+			if uint32(cv>>8) == load32(src, candidate2) {
+				table[hash2] = uint32(s + 2)
+				candidate = candidate2
+				s++
+				break
+			}
+			table[hash2] = uint32(s + 2)
+			if uint32(cv>>16) == load32(src, candidate) {
+				s += 2
+				break
+			}
+
+			cv = load64(src, nextS)
+			s = nextS
+		}
+
+		// Extend backwards
+		for candidate > 0 && s > nextEmit && src[candidate-1] == src[s-1] {
+			candidate--
+			s--
+		}
+
+		// Bail if we exceed the maximum size.
+		if d+(s-nextEmit) > dstLimit {
+			return 0
+		}
+
+		// A 4-byte match has been found. We'll later see if more than 4 bytes
+		// match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
+		// them as literal bytes.
+
+		d += emitLiteralSize(src[nextEmit:s])
+
+		// Call emitCopy, and then see if another emitCopy could be our next
+		// move. Repeat until we find no match for the input immediately after
+		// what was consumed by the last emitCopy call.
+		//
+		// If we exit this loop normally then we need to call emitLiteral next,
+		// though we don't yet know how big the literal will be. We handle that
+		// by proceeding to the next iteration of the main loop. We also can
+		// exit this loop via goto if we get close to exhausting the input.
+		for {
+			// Invariant: we have a 4-byte match at s, and no need to emit any
+			// literal bytes prior to s.
+			base := s
+			repeat = base - candidate
+
+			// Extend the 4-byte match as long as possible.
+			s += 4
+			candidate += 4
+			for s <= len(src)-8 {
+				if diff := load64(src, s) ^ load64(src, candidate); diff != 0 {
+					s += bits.TrailingZeros64(diff) >> 3
+					break
+				}
+				s += 8
+				candidate += 8
+			}
+
+			d += emitCopyNoRepeatSize(repeat, s-base)
+			if false {
+				// Validate match.
+				a := src[base:s]
+				b := src[base-repeat : base-repeat+(s-base)]
+				if !bytes.Equal(a, b) {
+					panic("mismatch")
+				}
+			}
+
+			nextEmit = s
+			if s >= sLimit {
+				goto emitRemainder
+			}
+
+			if d > dstLimit {
+				// Do we have space for more, if not bail.
+				return 0
+			}
+			// Check for an immediate match, otherwise start search at s+1
+			x := load64(src, s-2)
+			m2Hash := hash6(x, tableBits)
+			currHash := hash6(x>>16, tableBits)
+			candidate = int(table[currHash])
+			table[m2Hash] = uint32(s - 2)
+			table[currHash] = uint32(s)
+			if uint32(x>>16) != load32(src, candidate) {
+				cv = load64(src, s+1)
+				s++
+				break
+			}
+		}
+	}
+
+emitRemainder:
+	if nextEmit < len(src) {
+		// Bail if we exceed the maximum size.
+		if d+len(src)-nextEmit > dstLimit {
+			return 0
+		}
+		d += emitLiteralSize(src[nextEmit:])
+	}
+	return d
+}
+
+// length must be > inputMargin.
+func calcBlockSizeSmall(src []byte) (d int) {
+	// Initialize the hash table.
+	const (
+		tableBits    = 9
+		maxTableSize = 1 << tableBits
+	)
+
+	var table [maxTableSize]uint32
+
+	// sLimit is when to stop looking for offset/length copies. The inputMargin
+	// lets us use a fast path for emitLiteral in the main loop, while we are
+	// looking for copies.
+	sLimit := len(src) - inputMargin
+
+	// Bail if we can't compress to at least this.
+	dstLimit := len(src) - len(src)>>5 - 5
+
+	// nextEmit is where in src the next emitLiteral should start from.
+	nextEmit := 0
+
+	// The encoded form must start with a literal, as there are no previous
+	// bytes to copy, so we start looking for hash matches at s == 1.
+	s := 1
+	cv := load64(src, s)
+
+	// We search for a repeat at -1, but don't output repeats when nextEmit == 0
+	repeat := 1
+
+	for {
+		candidate := 0
+		for {
+			// Next src position to check
+			nextS := s + (s-nextEmit)>>6 + 4
+			if nextS > sLimit {
+				goto emitRemainder
+			}
+			hash0 := hash6(cv, tableBits)
+			hash1 := hash6(cv>>8, tableBits)
+			candidate = int(table[hash0])
+			candidate2 := int(table[hash1])
+			table[hash0] = uint32(s)
+			table[hash1] = uint32(s + 1)
+			hash2 := hash6(cv>>16, tableBits)
+
+			// Check repeat at offset checkRep.
+			const checkRep = 1
+			if uint32(cv>>(checkRep*8)) == load32(src, s-repeat+checkRep) {
+				base := s + checkRep
+				// Extend back
+				for i := base - repeat; base > nextEmit && i > 0 && src[i-1] == src[base-1]; {
+					i--
+					base--
+				}
+				d += emitLiteralSize(src[nextEmit:base])
+
+				// Extend forward
+				candidate := s - repeat + 4 + checkRep
+				s += 4 + checkRep
+				for s <= sLimit {
+					if diff := load64(src, s) ^ load64(src, candidate); diff != 0 {
+						s += bits.TrailingZeros64(diff) >> 3
+						break
+					}
+					s += 8
+					candidate += 8
+				}
+
+				d += emitCopyNoRepeatSize(repeat, s-base)
+				nextEmit = s
+				if s >= sLimit {
+					goto emitRemainder
+				}
+
+				cv = load64(src, s)
+				continue
+			}
+
+			if uint32(cv) == load32(src, candidate) {
+				break
+			}
+			candidate = int(table[hash2])
+			if uint32(cv>>8) == load32(src, candidate2) {
+				table[hash2] = uint32(s + 2)
+				candidate = candidate2
+				s++
+				break
+			}
+			table[hash2] = uint32(s + 2)
+			if uint32(cv>>16) == load32(src, candidate) {
+				s += 2
+				break
+			}
+
+			cv = load64(src, nextS)
+			s = nextS
+		}
+
+		// Extend backwards
+		for candidate > 0 && s > nextEmit && src[candidate-1] == src[s-1] {
+			candidate--
+			s--
+		}
+
+		// Bail if we exceed the maximum size.
+		if d+(s-nextEmit) > dstLimit {
+			return 0
+		}
+
+		// A 4-byte match has been found. We'll later see if more than 4 bytes
+		// match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
+		// them as literal bytes.
+
+		d += emitLiteralSize(src[nextEmit:s])
+
+		// Call emitCopy, and then see if another emitCopy could be our next
+		// move. Repeat until we find no match for the input immediately after
+		// what was consumed by the last emitCopy call.
+		//
+		// If we exit this loop normally then we need to call emitLiteral next,
+		// though we don't yet know how big the literal will be. We handle that
+		// by proceeding to the next iteration of the main loop. We also can
+		// exit this loop via goto if we get close to exhausting the input.
+		for {
+			// Invariant: we have a 4-byte match at s, and no need to emit any
+			// literal bytes prior to s.
+			base := s
+			repeat = base - candidate
+
+			// Extend the 4-byte match as long as possible.
+			s += 4
+			candidate += 4
+			for s <= len(src)-8 {
+				if diff := load64(src, s) ^ load64(src, candidate); diff != 0 {
+					s += bits.TrailingZeros64(diff) >> 3
+					break
+				}
+				s += 8
+				candidate += 8
+			}
+
+			d += emitCopyNoRepeatSize(repeat, s-base)
+			if false {
+				// Validate match.
+				a := src[base:s]
+				b := src[base-repeat : base-repeat+(s-base)]
+				if !bytes.Equal(a, b) {
+					panic("mismatch")
+				}
+			}
+
+			nextEmit = s
+			if s >= sLimit {
+				goto emitRemainder
+			}
+
+			if d > dstLimit {
+				// Do we have space for more, if not bail.
+				return 0
+			}
+			// Check for an immediate match, otherwise start search at s+1
+			x := load64(src, s-2)
+			m2Hash := hash6(x, tableBits)
+			currHash := hash6(x>>16, tableBits)
+			candidate = int(table[currHash])
+			table[m2Hash] = uint32(s - 2)
+			table[currHash] = uint32(s)
+			if uint32(x>>16) != load32(src, candidate) {
+				cv = load64(src, s+1)
+				s++
+				break
+			}
+		}
+	}
+
+emitRemainder:
+	if nextEmit < len(src) {
+		// Bail if we exceed the maximum size.
+		if d+len(src)-nextEmit > dstLimit {
+			return 0
+		}
+		d += emitLiteralSize(src[nextEmit:])
+	}
+	return d
+}
+
+// emitLiteral writes a literal chunk and returns the number of bytes written.
+//
+// It assumes that:
+//
+//	dst is long enough to hold the encoded bytes
+//	0 <= len(lit) && len(lit) <= math.MaxUint32
+func emitLiteralSize(lit []byte) int {
+	if len(lit) == 0 {
+		return 0
+	}
+	switch {
+	case len(lit) <= 60:
+		return len(lit) + 1
+	case len(lit) <= 1<<8:
+		return len(lit) + 2
+	case len(lit) <= 1<<16:
+		return len(lit) + 3
+	case len(lit) <= 1<<24:
+		return len(lit) + 4
+	default:
+		return len(lit) + 5
+	}
+}
+
+func cvtLZ4BlockAsm(dst []byte, src []byte) (uncompressed int, dstUsed int) {
+	panic("cvtLZ4BlockAsm should be unreachable")
+}
+
+func cvtLZ4BlockSnappyAsm(dst []byte, src []byte) (uncompressed int, dstUsed int) {
+	panic("cvtLZ4BlockSnappyAsm should be unreachable")
+}
+
+func cvtLZ4sBlockAsm(dst []byte, src []byte) (uncompressed int, dstUsed int) {
+	panic("cvtLZ4sBlockAsm should be unreachable")
+}
+
+func cvtLZ4sBlockSnappyAsm(dst []byte, src []byte) (uncompressed int, dstUsed int) {
+	panic("cvtLZ4sBlockSnappyAsm should be unreachable")
+}
-- 
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