libgo/go/strings/indexbyte.c

   1 /* indexbyte.c -- implement strings.IndexByte for Go.
   2
   3    Copyright 2013 The Go Authors. All rights reserved.
   4    Use of this source code is governed by a BSD-style
   5    license that can be found in the LICENSE file.  */
   6
   7 #include <stddef.h>
   8
   9 #include "runtime.h"
  10 #include "go-string.h"
  11
  12 /* This is in C so that the compiler can optimize it appropriately.
  13    We deliberately don't split the stack in case it does call the
  14    library function, which shouldn't need much stack space.  */
  15
  16 intgo IndexByte (String, char)
  17   __asm__ (GOSYM_PREFIX "strings.IndexByte")
  18   __attribute__ ((no_split_stack));
  19
  20 intgo
  21 IndexByte (String s, char b)
  22 {
  23   const char *p;
  24
  25   p = __builtin_memchr ((const char *) s.str, b, s.len);
  26   if (p == NULL)
  27     return -1;
  28   return p - (const char *) s.str;
  29 }