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 }