Source file src/vendor/golang.org/x/crypto/internal/chacha20/chacha_ppc64le.go

     1	// Copyright 2019 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	// +build ppc64le,!gccgo,!appengine
     6	
     7	package chacha20
     8	
     9	import "encoding/binary"
    10	
    11	const (
    12		bufSize = 256
    13		haveAsm = true
    14	)
    15	
    16	//go:noescape
    17	func chaCha20_ctr32_vmx(out, inp *byte, len int, key *[8]uint32, counter *uint32)
    18	
    19	func (c *Cipher) xorKeyStreamAsm(dst, src []byte) {
    20		if len(src) >= bufSize {
    21			chaCha20_ctr32_vmx(&dst[0], &src[0], len(src)-len(src)%bufSize, &c.key, &c.counter)
    22		}
    23		if len(src)%bufSize != 0 {
    24			chaCha20_ctr32_vmx(&c.buf[0], &c.buf[0], bufSize, &c.key, &c.counter)
    25			start := len(src) - len(src)%bufSize
    26			ts, td, tb := src[start:], dst[start:], c.buf[:]
    27			// Unroll loop to XOR 32 bytes per iteration.
    28			for i := 0; i < len(ts)-32; i += 32 {
    29				td, tb = td[:len(ts)], tb[:len(ts)] // bounds check elimination
    30				s0 := binary.LittleEndian.Uint64(ts[0:8])
    31				s1 := binary.LittleEndian.Uint64(ts[8:16])
    32				s2 := binary.LittleEndian.Uint64(ts[16:24])
    33				s3 := binary.LittleEndian.Uint64(ts[24:32])
    34				b0 := binary.LittleEndian.Uint64(tb[0:8])
    35				b1 := binary.LittleEndian.Uint64(tb[8:16])
    36				b2 := binary.LittleEndian.Uint64(tb[16:24])
    37				b3 := binary.LittleEndian.Uint64(tb[24:32])
    38				binary.LittleEndian.PutUint64(td[0:8], s0^b0)
    39				binary.LittleEndian.PutUint64(td[8:16], s1^b1)
    40				binary.LittleEndian.PutUint64(td[16:24], s2^b2)
    41				binary.LittleEndian.PutUint64(td[24:32], s3^b3)
    42				ts, td, tb = ts[32:], td[32:], tb[32:]
    43			}
    44			td, tb = td[:len(ts)], tb[:len(ts)] // bounds check elimination
    45			for i, v := range ts {
    46				td[i] = tb[i] ^ v
    47			}
    48			c.len = bufSize - (len(src) % bufSize)
    49	
    50		}
    51	
    52	}
    53	

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