libgo/runtime/go-int-array-to-string.c

   1 /* go-int-array-to-string.c -- convert an array of ints to a string in Go.
   2
   3    Copyright 2009 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 "go-assert.h"
   8 #include "go-string.h"
   9 #include "runtime.h"
  10 #include "malloc.h"
  11
  12 struct __go_string
  13 __go_int_array_to_string (const void* p, int len)
  14 {
  15   const int *ints;
  16   int slen;
  17   int i;
  18   unsigned char *retdata;
  19   struct __go_string ret;
  20   unsigned char *s;
  21
  22   ints = (const int *) p;
  23
  24   slen = 0;
  25   for (i = 0; i < len; ++i)
  26     {
  27       int v;
  28
  29       v = ints[i];
  30
  31       if (v > 0x10ffff)
  32         v = 0xfffd;
  33
  34       if (v <= 0x7f)
  35         slen += 1;
  36       else if (v <= 0x7ff)
  37         slen += 2;
  38       else if (v <= 0xffff)
  39         slen += 3;
  40       else
  41         slen += 4;
  42     }
  43
  44   retdata = runtime_mallocgc (slen, FlagNoPointers, 1, 0);
  45   ret.__data = retdata;
  46   ret.__length = slen;
  47
  48   s = retdata;
  49   for (i = 0; i < len; ++i)
  50     {
  51       int v;
  52
  53       v = ints[i];
  54
  55       /* If V is out of range for UTF-8, substitute the replacement
  56          character.  */
  57       if (v > 0x10ffff)
  58         v = 0xfffd;
  59
  60       if (v <= 0x7f)
  61         *s++ = v;
  62       else if (v <= 0x7ff)
  63         {
  64           *s++ = 0xc0 | ((v >> 6) & 0x1f);
  65           *s++ = 0x80 | (v & 0x3f);
  66         }
  67       else if (v <= 0xffff)
  68         {
  69           *s++ = 0xe0 | ((v >> 12) & 0xf);
  70           *s++ = 0x80 | ((v >> 6) & 0x3f);
  71           *s++ = 0x80 | (v & 0x3f);
  72         }
  73       else
  74         {
  75           *s++ = 0xf0 | ((v >> 18) & 0x7);
  76           *s++ = 0x80 | ((v >> 12) & 0x3f);
  77           *s++ = 0x80 | ((v >> 6) & 0x3f);
  78           *s++ = 0x80 | (v & 0x3f);
  79         }
  80     }
  81
  82   __go_assert (s - retdata == slen);
  83
  84   return ret;
  85 }