sum_amd64.go

     1  // Copyright 2012 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  //go:build gc && !purego
     6  
     7  package poly1305
     8  
     9  //go:noescape
    10  func update(state *macState, msg []byte)
    11  
    12  // mac is a wrapper for macGeneric that redirects calls that would have gone to
    13  // updateGeneric to update.
    14  //
    15  // Its Write and Sum methods are otherwise identical to the macGeneric ones, but
    16  // using function pointers would carry a major performance cost.
    17  type mac struct{ macGeneric }
    18  
    19  func (h *mac) Write(p []byte) (int, error) {
    20  	nn := len(p)
    21  	if h.offset > 0 {
    22  		n := copy(h.buffer[h.offset:], p)
    23  		if h.offset+n < TagSize {
    24  			h.offset += n
    25  			return nn, nil
    26  		}
    27  		p = p[n:]
    28  		h.offset = 0
    29  		update(&h.macState, h.buffer[:])
    30  	}
    31  	if n := len(p) - (len(p) % TagSize); n > 0 {
    32  		update(&h.macState, p[:n])
    33  		p = p[n:]
    34  	}
    35  	if len(p) > 0 {
    36  		h.offset += copy(h.buffer[h.offset:], p)
    37  	}
    38  	return nn, nil
    39  }
    40  
    41  func (h *mac) Sum(out *[16]byte) {
    42  	state := h.macState
    43  	if h.offset > 0 {
    44  		update(&state, h.buffer[:h.offset])
    45  	}
    46  	finalize(out, &state.h, &state.s)
    47  }
    48
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