[VOL-1386] This commit add "dep" as the package management tool
for voltha-go.
Change-Id: I52bc4911dd00a441756ec7c30f46d45091f3f90e
diff --git a/vendor/github.com/golang/snappy/decode_amd64.s b/vendor/github.com/golang/snappy/decode_amd64.s
new file mode 100644
index 0000000..e6179f6
--- /dev/null
+++ b/vendor/github.com/golang/snappy/decode_amd64.s
@@ -0,0 +1,490 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build !appengine
+// +build gc
+// +build !noasm
+
+#include "textflag.h"
+
+// The asm code generally follows the pure Go code in decode_other.go, except
+// where marked with a "!!!".
+
+// func decode(dst, src []byte) int
+//
+// All local variables fit into registers. The non-zero stack size is only to
+// spill registers and push args when issuing a CALL. The register allocation:
+// - AX scratch
+// - BX scratch
+// - CX length or x
+// - DX offset
+// - SI &src[s]
+// - DI &dst[d]
+// + R8 dst_base
+// + R9 dst_len
+// + R10 dst_base + dst_len
+// + R11 src_base
+// + R12 src_len
+// + R13 src_base + src_len
+// - R14 used by doCopy
+// - R15 used by doCopy
+//
+// The registers R8-R13 (marked with a "+") are set at the start of the
+// function, and after a CALL returns, and are not otherwise modified.
+//
+// The d variable is implicitly DI - R8, and len(dst)-d is R10 - DI.
+// The s variable is implicitly SI - R11, and len(src)-s is R13 - SI.
+TEXT ·decode(SB), NOSPLIT, $48-56
+ // Initialize SI, DI and R8-R13.
+ MOVQ dst_base+0(FP), R8
+ MOVQ dst_len+8(FP), R9
+ MOVQ R8, DI
+ MOVQ R8, R10
+ ADDQ R9, R10
+ MOVQ src_base+24(FP), R11
+ MOVQ src_len+32(FP), R12
+ MOVQ R11, SI
+ MOVQ R11, R13
+ ADDQ R12, R13
+
+loop:
+ // for s < len(src)
+ CMPQ SI, R13
+ JEQ end
+
+ // CX = uint32(src[s])
+ //
+ // switch src[s] & 0x03
+ MOVBLZX (SI), CX
+ MOVL CX, BX
+ ANDL $3, BX
+ CMPL BX, $1
+ JAE tagCopy
+
+ // ----------------------------------------
+ // The code below handles literal tags.
+
+ // case tagLiteral:
+ // x := uint32(src[s] >> 2)
+ // switch
+ SHRL $2, CX
+ CMPL CX, $60
+ JAE tagLit60Plus
+
+ // case x < 60:
+ // s++
+ INCQ SI
+
+doLit:
+ // This is the end of the inner "switch", when we have a literal tag.
+ //
+ // We assume that CX == x and x fits in a uint32, where x is the variable
+ // used in the pure Go decode_other.go code.
+
+ // length = int(x) + 1
+ //
+ // Unlike the pure Go code, we don't need to check if length <= 0 because
+ // CX can hold 64 bits, so the increment cannot overflow.
+ INCQ CX
+
+ // Prepare to check if copying length bytes will run past the end of dst or
+ // src.
+ //
+ // AX = len(dst) - d
+ // BX = len(src) - s
+ MOVQ R10, AX
+ SUBQ DI, AX
+ MOVQ R13, BX
+ SUBQ SI, BX
+
+ // !!! Try a faster technique for short (16 or fewer bytes) copies.
+ //
+ // if length > 16 || len(dst)-d < 16 || len(src)-s < 16 {
+ // goto callMemmove // Fall back on calling runtime·memmove.
+ // }
+ //
+ // The C++ snappy code calls this TryFastAppend. It also checks len(src)-s
+ // against 21 instead of 16, because it cannot assume that all of its input
+ // is contiguous in memory and so it needs to leave enough source bytes to
+ // read the next tag without refilling buffers, but Go's Decode assumes
+ // contiguousness (the src argument is a []byte).
+ CMPQ CX, $16
+ JGT callMemmove
+ CMPQ AX, $16
+ JLT callMemmove
+ CMPQ BX, $16
+ JLT callMemmove
+
+ // !!! Implement the copy from src to dst as a 16-byte load and store.
+ // (Decode's documentation says that dst and src must not overlap.)
+ //
+ // This always copies 16 bytes, instead of only length bytes, but that's
+ // OK. If the input is a valid Snappy encoding then subsequent iterations
+ // will fix up the overrun. Otherwise, Decode returns a nil []byte (and a
+ // non-nil error), so the overrun will be ignored.
+ //
+ // Note that on amd64, it is legal and cheap to issue unaligned 8-byte or
+ // 16-byte loads and stores. This technique probably wouldn't be as
+ // effective on architectures that are fussier about alignment.
+ MOVOU 0(SI), X0
+ MOVOU X0, 0(DI)
+
+ // d += length
+ // s += length
+ ADDQ CX, DI
+ ADDQ CX, SI
+ JMP loop
+
+callMemmove:
+ // if length > len(dst)-d || length > len(src)-s { etc }
+ CMPQ CX, AX
+ JGT errCorrupt
+ CMPQ CX, BX
+ JGT errCorrupt
+
+ // copy(dst[d:], src[s:s+length])
+ //
+ // This means calling runtime·memmove(&dst[d], &src[s], length), so we push
+ // DI, SI and CX as arguments. Coincidentally, we also need to spill those
+ // three registers to the stack, to save local variables across the CALL.
+ MOVQ DI, 0(SP)
+ MOVQ SI, 8(SP)
+ MOVQ CX, 16(SP)
+ MOVQ DI, 24(SP)
+ MOVQ SI, 32(SP)
+ MOVQ CX, 40(SP)
+ CALL runtime·memmove(SB)
+
+ // Restore local variables: unspill registers from the stack and
+ // re-calculate R8-R13.
+ MOVQ 24(SP), DI
+ MOVQ 32(SP), SI
+ MOVQ 40(SP), CX
+ MOVQ dst_base+0(FP), R8
+ MOVQ dst_len+8(FP), R9
+ MOVQ R8, R10
+ ADDQ R9, R10
+ MOVQ src_base+24(FP), R11
+ MOVQ src_len+32(FP), R12
+ MOVQ R11, R13
+ ADDQ R12, R13
+
+ // d += length
+ // s += length
+ ADDQ CX, DI
+ ADDQ CX, SI
+ JMP loop
+
+tagLit60Plus:
+ // !!! This fragment does the
+ //
+ // s += x - 58; if uint(s) > uint(len(src)) { etc }
+ //
+ // checks. In the asm version, we code it once instead of once per switch case.
+ ADDQ CX, SI
+ SUBQ $58, SI
+ MOVQ SI, BX
+ SUBQ R11, BX
+ CMPQ BX, R12
+ JA errCorrupt
+
+ // case x == 60:
+ CMPL CX, $61
+ JEQ tagLit61
+ JA tagLit62Plus
+
+ // x = uint32(src[s-1])
+ MOVBLZX -1(SI), CX
+ JMP doLit
+
+tagLit61:
+ // case x == 61:
+ // x = uint32(src[s-2]) | uint32(src[s-1])<<8
+ MOVWLZX -2(SI), CX
+ JMP doLit
+
+tagLit62Plus:
+ CMPL CX, $62
+ JA tagLit63
+
+ // case x == 62:
+ // x = uint32(src[s-3]) | uint32(src[s-2])<<8 | uint32(src[s-1])<<16
+ MOVWLZX -3(SI), CX
+ MOVBLZX -1(SI), BX
+ SHLL $16, BX
+ ORL BX, CX
+ JMP doLit
+
+tagLit63:
+ // case x == 63:
+ // x = uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24
+ MOVL -4(SI), CX
+ JMP doLit
+
+// The code above handles literal tags.
+// ----------------------------------------
+// The code below handles copy tags.
+
+tagCopy4:
+ // case tagCopy4:
+ // s += 5
+ ADDQ $5, SI
+
+ // if uint(s) > uint(len(src)) { etc }
+ MOVQ SI, BX
+ SUBQ R11, BX
+ CMPQ BX, R12
+ JA errCorrupt
+
+ // length = 1 + int(src[s-5])>>2
+ SHRQ $2, CX
+ INCQ CX
+
+ // offset = int(uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24)
+ MOVLQZX -4(SI), DX
+ JMP doCopy
+
+tagCopy2:
+ // case tagCopy2:
+ // s += 3
+ ADDQ $3, SI
+
+ // if uint(s) > uint(len(src)) { etc }
+ MOVQ SI, BX
+ SUBQ R11, BX
+ CMPQ BX, R12
+ JA errCorrupt
+
+ // length = 1 + int(src[s-3])>>2
+ SHRQ $2, CX
+ INCQ CX
+
+ // offset = int(uint32(src[s-2]) | uint32(src[s-1])<<8)
+ MOVWQZX -2(SI), DX
+ JMP doCopy
+
+tagCopy:
+ // We have a copy tag. We assume that:
+ // - BX == src[s] & 0x03
+ // - CX == src[s]
+ CMPQ BX, $2
+ JEQ tagCopy2
+ JA tagCopy4
+
+ // case tagCopy1:
+ // s += 2
+ ADDQ $2, SI
+
+ // if uint(s) > uint(len(src)) { etc }
+ MOVQ SI, BX
+ SUBQ R11, BX
+ CMPQ BX, R12
+ JA errCorrupt
+
+ // offset = int(uint32(src[s-2])&0xe0<<3 | uint32(src[s-1]))
+ MOVQ CX, DX
+ ANDQ $0xe0, DX
+ SHLQ $3, DX
+ MOVBQZX -1(SI), BX
+ ORQ BX, DX
+
+ // length = 4 + int(src[s-2])>>2&0x7
+ SHRQ $2, CX
+ ANDQ $7, CX
+ ADDQ $4, CX
+
+doCopy:
+ // This is the end of the outer "switch", when we have a copy tag.
+ //
+ // We assume that:
+ // - CX == length && CX > 0
+ // - DX == offset
+
+ // if offset <= 0 { etc }
+ CMPQ DX, $0
+ JLE errCorrupt
+
+ // if d < offset { etc }
+ MOVQ DI, BX
+ SUBQ R8, BX
+ CMPQ BX, DX
+ JLT errCorrupt
+
+ // if length > len(dst)-d { etc }
+ MOVQ R10, BX
+ SUBQ DI, BX
+ CMPQ CX, BX
+ JGT errCorrupt
+
+ // forwardCopy(dst[d:d+length], dst[d-offset:]); d += length
+ //
+ // Set:
+ // - R14 = len(dst)-d
+ // - R15 = &dst[d-offset]
+ MOVQ R10, R14
+ SUBQ DI, R14
+ MOVQ DI, R15
+ SUBQ DX, R15
+
+ // !!! Try a faster technique for short (16 or fewer bytes) forward copies.
+ //
+ // First, try using two 8-byte load/stores, similar to the doLit technique
+ // above. Even if dst[d:d+length] and dst[d-offset:] can overlap, this is
+ // still OK if offset >= 8. Note that this has to be two 8-byte load/stores
+ // and not one 16-byte load/store, and the first store has to be before the
+ // second load, due to the overlap if offset is in the range [8, 16).
+ //
+ // if length > 16 || offset < 8 || len(dst)-d < 16 {
+ // goto slowForwardCopy
+ // }
+ // copy 16 bytes
+ // d += length
+ CMPQ CX, $16
+ JGT slowForwardCopy
+ CMPQ DX, $8
+ JLT slowForwardCopy
+ CMPQ R14, $16
+ JLT slowForwardCopy
+ MOVQ 0(R15), AX
+ MOVQ AX, 0(DI)
+ MOVQ 8(R15), BX
+ MOVQ BX, 8(DI)
+ ADDQ CX, DI
+ JMP loop
+
+slowForwardCopy:
+ // !!! If the forward copy is longer than 16 bytes, or if offset < 8, we
+ // can still try 8-byte load stores, provided we can overrun up to 10 extra
+ // bytes. As above, the overrun will be fixed up by subsequent iterations
+ // of the outermost loop.
+ //
+ // The C++ snappy code calls this technique IncrementalCopyFastPath. Its
+ // commentary says:
+ //
+ // ----
+ //
+ // The main part of this loop is a simple copy of eight bytes at a time
+ // until we've copied (at least) the requested amount of bytes. However,
+ // if d and d-offset are less than eight bytes apart (indicating a
+ // repeating pattern of length < 8), we first need to expand the pattern in
+ // order to get the correct results. For instance, if the buffer looks like
+ // this, with the eight-byte <d-offset> and <d> patterns marked as
+ // intervals:
+ //
+ // abxxxxxxxxxxxx
+ // [------] d-offset
+ // [------] d
+ //
+ // a single eight-byte copy from <d-offset> to <d> will repeat the pattern
+ // once, after which we can move <d> two bytes without moving <d-offset>:
+ //
+ // ababxxxxxxxxxx
+ // [------] d-offset
+ // [------] d
+ //
+ // and repeat the exercise until the two no longer overlap.
+ //
+ // This allows us to do very well in the special case of one single byte
+ // repeated many times, without taking a big hit for more general cases.
+ //
+ // The worst case of extra writing past the end of the match occurs when
+ // offset == 1 and length == 1; the last copy will read from byte positions
+ // [0..7] and write to [4..11], whereas it was only supposed to write to
+ // position 1. Thus, ten excess bytes.
+ //
+ // ----
+ //
+ // That "10 byte overrun" worst case is confirmed by Go's
+ // TestSlowForwardCopyOverrun, which also tests the fixUpSlowForwardCopy
+ // and finishSlowForwardCopy algorithm.
+ //
+ // if length > len(dst)-d-10 {
+ // goto verySlowForwardCopy
+ // }
+ SUBQ $10, R14
+ CMPQ CX, R14
+ JGT verySlowForwardCopy
+
+makeOffsetAtLeast8:
+ // !!! As above, expand the pattern so that offset >= 8 and we can use
+ // 8-byte load/stores.
+ //
+ // for offset < 8 {
+ // copy 8 bytes from dst[d-offset:] to dst[d:]
+ // length -= offset
+ // d += offset
+ // offset += offset
+ // // The two previous lines together means that d-offset, and therefore
+ // // R15, is unchanged.
+ // }
+ CMPQ DX, $8
+ JGE fixUpSlowForwardCopy
+ MOVQ (R15), BX
+ MOVQ BX, (DI)
+ SUBQ DX, CX
+ ADDQ DX, DI
+ ADDQ DX, DX
+ JMP makeOffsetAtLeast8
+
+fixUpSlowForwardCopy:
+ // !!! Add length (which might be negative now) to d (implied by DI being
+ // &dst[d]) so that d ends up at the right place when we jump back to the
+ // top of the loop. Before we do that, though, we save DI to AX so that, if
+ // length is positive, copying the remaining length bytes will write to the
+ // right place.
+ MOVQ DI, AX
+ ADDQ CX, DI
+
+finishSlowForwardCopy:
+ // !!! Repeat 8-byte load/stores until length <= 0. Ending with a negative
+ // length means that we overrun, but as above, that will be fixed up by
+ // subsequent iterations of the outermost loop.
+ CMPQ CX, $0
+ JLE loop
+ MOVQ (R15), BX
+ MOVQ BX, (AX)
+ ADDQ $8, R15
+ ADDQ $8, AX
+ SUBQ $8, CX
+ JMP finishSlowForwardCopy
+
+verySlowForwardCopy:
+ // verySlowForwardCopy is a simple implementation of forward copy. In C
+ // parlance, this is a do/while loop instead of a while loop, since we know
+ // that length > 0. In Go syntax:
+ //
+ // for {
+ // dst[d] = dst[d - offset]
+ // d++
+ // length--
+ // if length == 0 {
+ // break
+ // }
+ // }
+ MOVB (R15), BX
+ MOVB BX, (DI)
+ INCQ R15
+ INCQ DI
+ DECQ CX
+ JNZ verySlowForwardCopy
+ JMP loop
+
+// The code above handles copy tags.
+// ----------------------------------------
+
+end:
+ // This is the end of the "for s < len(src)".
+ //
+ // if d != len(dst) { etc }
+ CMPQ DI, R10
+ JNE errCorrupt
+
+ // return 0
+ MOVQ $0, ret+48(FP)
+ RET
+
+errCorrupt:
+ // return decodeErrCodeCorrupt
+ MOVQ $1, ret+48(FP)
+ RET