435c0d9fc8
This PR switches the Nomad repository from using govendor to Go modules for managing dependencies. Aspects of the Nomad workflow remain pretty much the same. The usual Makefile targets should continue to work as they always did. The API submodule simply defers to the parent Nomad version on the repository, keeping the semantics of API versioning that currently exists.
93 lines
1.9 KiB
Go
93 lines
1.9 KiB
Go
// +build !amd64 appengine !gc noasm
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package lz4
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func decodeBlock(dst, src []byte) (ret int) {
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const hasError = -2
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defer func() {
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if recover() != nil {
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ret = hasError
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}
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}()
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var si, di int
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for {
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// Literals and match lengths (token).
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b := int(src[si])
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si++
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// Literals.
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if lLen := b >> 4; lLen > 0 {
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switch {
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case lLen < 0xF && di+18 < len(dst) && si+16 < len(src):
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// Shortcut 1
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// if we have enough room in src and dst, and the literals length
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// is small enough (0..14) then copy all 16 bytes, even if not all
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// are part of the literals.
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copy(dst[di:], src[si:si+16])
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si += lLen
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di += lLen
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if mLen := b & 0xF; mLen < 0xF {
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// Shortcut 2
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// if the match length (4..18) fits within the literals, then copy
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// all 18 bytes, even if not all are part of the literals.
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mLen += 4
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if offset := int(src[si]) | int(src[si+1])<<8; mLen <= offset {
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i := di - offset
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copy(dst[di:], dst[i:i+18])
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si += 2
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di += mLen
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continue
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}
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}
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case lLen == 0xF:
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for src[si] == 0xFF {
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lLen += 0xFF
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si++
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}
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lLen += int(src[si])
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si++
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fallthrough
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default:
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copy(dst[di:di+lLen], src[si:si+lLen])
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si += lLen
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di += lLen
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}
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}
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if si >= len(src) {
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return di
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}
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offset := int(src[si]) | int(src[si+1])<<8
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if offset == 0 {
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return hasError
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}
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si += 2
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// Match.
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mLen := b & 0xF
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if mLen == 0xF {
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for src[si] == 0xFF {
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mLen += 0xFF
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si++
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}
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mLen += int(src[si])
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si++
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}
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mLen += minMatch
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// Copy the match.
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expanded := dst[di-offset:]
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if mLen > offset {
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// Efficiently copy the match dst[di-offset:di] into the dst slice.
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bytesToCopy := offset * (mLen / offset)
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for n := offset; n <= bytesToCopy+offset; n *= 2 {
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copy(expanded[n:], expanded[:n])
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}
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di += bytesToCopy
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mLen -= bytesToCopy
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}
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di += copy(dst[di:di+mLen], expanded[:mLen])
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}
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}
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