golang sum_amd64 代码
文件路径：/src/vendor/golang.org/x/crypto/internal/poly1305/sum_amd64.go
/ Copyright 2012 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.
/go:build gc && !purego
/ +build gc,!purego
package poly1305
/go:noescape
func update(state *macState, msg []byte)
/ mac is a wrapper for macGeneric that redirects calls that would have gone to
/ updateGeneric to update.
/
/ Its Write and Sum methods are otherwise identical to the macGeneric ones, but
/ using function pointers would carry a major performance cost.
type mac struct{ macGeneric }
func (h *mac) Write(p []byte) (int, error) {
nn := len(p)
if h.offset > 0 {
n := copy(h.buffer[h.offset:], p)
if h.offset+n < TagSize {
h.offset += n
return nn, nil
}
p = p[n:]
h.offset = 0
update(&h.macState, h.buffer[:])
}
if n := len(p) - (len(p) % TagSize); n > 0 {
update(&h.macState, p[:n])
p = p[n:]
}
if len(p) > 0 {
h.offset += copy(h.buffer[h.offset:], p)
}
return nn, nil
}
func (h *mac) Sum(out *[16]byte) {
state := h.macState
if h.offset > 0 {
update(&state, h.buffer[:h.offset])
}
finalize(out, &state.h, &state.s)
}