index_s390x.go

     1  // Copyright 2018 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  package bytealg
     6  
     7  import "internal/cpu"
     8  
     9  const MaxBruteForce = 64
    10  
    11  func init() {
    12  	// Note: we're kind of lucky that this flag is available at this point.
    13  	// The runtime sets HasVX when processing auxv records, and that happens
    14  	// to happen *before* running the init functions of packages that
    15  	// the runtime depends on.
    16  	// TODO: it would really be nicer for internal/cpu to figure out this
    17  	// flag by itself. Then we wouldn't need to depend on quirks of
    18  	// early startup initialization order.
    19  	if cpu.S390X.HasVX {
    20  		MaxLen = 64
    21  	}
    22  }
    23  
    24  // Cutover reports the number of failures of IndexByte we should tolerate
    25  // before switching over to Index.
    26  // n is the number of bytes processed so far.
    27  // See the bytes.Index implementation for details.
    28  func Cutover(n int) int {
    29  	// 1 error per 8 characters, plus a few slop to start.
    30  	return (n + 16) / 8
    31  }
    32
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