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.
76 lines
2 KiB
Go
76 lines
2 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build !gccgo,!purego
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package poly1305
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import (
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"golang.org/x/sys/cpu"
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)
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// updateVX is an assembly implementation of Poly1305 that uses vector
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// instructions. It must only be called if the vector facility (vx) is
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// available.
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//go:noescape
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func updateVX(state *macState, msg []byte)
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// mac is a replacement for macGeneric that uses a larger buffer and redirects
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// calls that would have gone to updateGeneric to updateVX if the vector
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// facility is installed.
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//
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// A larger buffer is required for good performance because the vector
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// implementation has a higher fixed cost per call than the generic
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// implementation.
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type mac struct {
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macState
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buffer [16 * TagSize]byte // size must be a multiple of block size (16)
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offset int
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}
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func (h *mac) Write(p []byte) (int, error) {
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nn := len(p)
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if h.offset > 0 {
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n := copy(h.buffer[h.offset:], p)
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if h.offset+n < len(h.buffer) {
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h.offset += n
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return nn, nil
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}
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p = p[n:]
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h.offset = 0
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if cpu.S390X.HasVX {
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updateVX(&h.macState, h.buffer[:])
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} else {
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updateGeneric(&h.macState, h.buffer[:])
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}
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}
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tail := len(p) % len(h.buffer) // number of bytes to copy into buffer
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body := len(p) - tail // number of bytes to process now
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if body > 0 {
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if cpu.S390X.HasVX {
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updateVX(&h.macState, p[:body])
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} else {
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updateGeneric(&h.macState, p[:body])
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}
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}
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h.offset = copy(h.buffer[:], p[body:]) // copy tail bytes - can be 0
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return nn, nil
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}
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func (h *mac) Sum(out *[TagSize]byte) {
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state := h.macState
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remainder := h.buffer[:h.offset]
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// Use the generic implementation if we have 2 or fewer blocks left
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// to sum. The vector implementation has a higher startup time.
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if cpu.S390X.HasVX && len(remainder) > 2*TagSize {
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updateVX(&state, remainder)
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} else if len(remainder) > 0 {
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updateGeneric(&state, remainder)
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}
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finalize(out, &state.h, &state.s)
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}
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