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  // +build gc,!purego
     7  
     8  package poly1305
     9  
    10  //go:noescape
    11  func update(state *macState, msg []byte)
    12  
    13  // mac is a wrapper for macGeneric that redirects calls that would have gone to
    14  // updateGeneric to update.
    15  //
    16  // Its Write and Sum methods are otherwise identical to the macGeneric ones, but
    17  // using function pointers would carry a major performance cost.
    18  type mac struct{ macGeneric }
    19  
    20  func (h *mac) Write(p []byte) (int, error) {
    21  	nn := len(p)
    22  	if h.offset > 0 {
    23  		n := copy(h.buffer[h.offset:], p)
    24  		if h.offset+n < TagSize {
    25  			h.offset += n
    26  			return nn, nil
    27  		}
    28  		p = p[n:]
    29  		h.offset = 0
    30  		update(&h.macState, h.buffer[:])
    31  	}
    32  	if n := len(p) - (len(p) % TagSize); n > 0 {
    33  		update(&h.macState, p[:n])
    34  		p = p[n:]
    35  	}
    36  	if len(p) > 0 {
    37  		h.offset += copy(h.buffer[h.offset:], p)
    38  	}
    39  	return nn, nil
    40  }
    41  
    42  func (h *mac) Sum(out *[16]byte) {
    43  	state := h.macState
    44  	if h.offset > 0 {
    45  		update(&state, h.buffer[:h.offset])
    46  	}
    47  	finalize(out, &state.h, &state.s)
    48  }
    49
View as plain text