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

   1 /* go-int-to-string.c -- convert an integer 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-string.h"
   8 #include "runtime.h"
   9 #include "arch.h"
  10 #include "malloc.h"
  11
  12 struct __go_string
  13 __go_int_to_string (int v)
  14 {
  15   char buf[4];
  16   int len;
  17   unsigned char *retdata;
  18   struct __go_string ret;
  19
  20   if (v <= 0x7f)
  21     {
  22       buf[0] = v;
  23       len = 1;
  24     }
  25   else if (v <= 0x7ff)
  26     {
  27       buf[0] = 0xc0 + (v >> 6);
  28       buf[1] = 0x80 + (v & 0x3f);
  29       len = 2;
  30     }
  31   else
  32     {
  33       /* If the value is out of range for UTF-8, turn it into the
  34          "replacement character".  */
  35       if (v > 0x10ffff)
  36         v = 0xfffd;
  37
  38       if (v <= 0xffff)
  39         {
  40           buf[0] = 0xe0 + (v >> 12);
  41           buf[1] = 0x80 + ((v >> 6) & 0x3f);
  42           buf[2] = 0x80 + (v & 0x3f);
  43           len = 3;
  44         }
  45       else
  46         {
  47           buf[0] = 0xf0 + (v >> 18);
  48           buf[1] = 0x80 + ((v >> 12) & 0x3f);
  49           buf[2] = 0x80 + ((v >> 6) & 0x3f);
  50           buf[3] = 0x80 + (v & 0x3f);
  51           len = 4;
  52         }
  53     }
  54
  55   retdata = runtime_mallocgc (len, FlagNoPointers, 1, 0);
  56   __builtin_memcpy (retdata, buf, len);
  57   ret.__data = retdata;
  58   ret.__length = len;
  59
  60   return ret;
  61 }