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 "runtime.h"
8 #include "arch.h"
9 #include "malloc.h"
10 
11 String
__go_int_to_string(intgo v)12 __go_int_to_string (intgo v)
13 {
14   char buf[4];
15   int len;
16   unsigned char *retdata;
17   String ret;
18 
19   /* A negative value is not valid UTF-8; turn it into the replacement
20      character.  */
21   if (v < 0)
22     v = 0xfffd;
23 
24   if (v <= 0x7f)
25     {
26       buf[0] = v;
27       len = 1;
28     }
29   else if (v <= 0x7ff)
30     {
31       buf[0] = 0xc0 + (v >> 6);
32       buf[1] = 0x80 + (v & 0x3f);
33       len = 2;
34     }
35   else
36     {
37       /* If the value is out of range for UTF-8, turn it into the
38 	 "replacement character".  */
39       if (v > 0x10ffff)
40 	v = 0xfffd;
41       /* If the value is a surrogate pair, which is invalid in UTF-8,
42 	 turn it into the replacement character.  */
43       if (v >= 0xd800 && v < 0xe000)
44 	v = 0xfffd;
45 
46       if (v <= 0xffff)
47 	{
48 	  buf[0] = 0xe0 + (v >> 12);
49 	  buf[1] = 0x80 + ((v >> 6) & 0x3f);
50 	  buf[2] = 0x80 + (v & 0x3f);
51 	  len = 3;
52 	}
53       else
54 	{
55 	  buf[0] = 0xf0 + (v >> 18);
56 	  buf[1] = 0x80 + ((v >> 12) & 0x3f);
57 	  buf[2] = 0x80 + ((v >> 6) & 0x3f);
58 	  buf[3] = 0x80 + (v & 0x3f);
59 	  len = 4;
60 	}
61     }
62 
63   retdata = runtime_mallocgc (len, 0, FlagNoScan);
64   __builtin_memcpy (retdata, buf, len);
65   ret.str = retdata;
66   ret.len = len;
67 
68   return ret;
69 }
70