1 /*
2 cencoder.c - c source to a base64 encoding algorithm implementation
3
4 This is part of the libb64 project, and has been placed in the public domain.
5 For details, see http://sourceforge.net/projects/libb64
6 */
7
8 #include "b64/cencode.h"
9
base64_init_encodestate(base64_encodestate * state_in)10 void base64_init_encodestate(base64_encodestate* state_in)
11 {
12 state_in->step = step_A;
13 state_in->result = 0;
14 state_in->stepcount = 0;
15 }
16
base64_encode_value(char value_in)17 char base64_encode_value(char value_in)
18 {
19 static const char* encoding = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
20 if (value_in > 63) return '=';
21 return encoding[(int)value_in];
22 }
23
base64_encode_block(const char * plaintext_in,int length_in,char * code_out,base64_encodestate * state_in)24 int base64_encode_block(const char* plaintext_in, int length_in, char* code_out, base64_encodestate* state_in)
25 {
26 const char* plainchar = plaintext_in;
27 const char* const plaintextend = plaintext_in + length_in;
28 char* codechar = code_out;
29 char result;
30 char fragment;
31
32 result = state_in->result;
33
34 switch (state_in->step)
35 {
36 while (1)
37 {
38 case step_A:
39 if (plainchar == plaintextend)
40 {
41 state_in->result = result;
42 state_in->step = step_A;
43 return (int)(codechar - code_out);
44 }
45 fragment = *plainchar++;
46 result = (fragment & 0x0fc) >> 2;
47 *codechar++ = base64_encode_value(result);
48 result = (fragment & 0x003) << 4;
49 /* fall through */
50
51 case step_B:
52 if (plainchar == plaintextend)
53 {
54 state_in->result = result;
55 state_in->step = step_B;
56 return (int)(codechar - code_out);
57 }
58 fragment = *plainchar++;
59 result |= (fragment & 0x0f0) >> 4;
60 *codechar++ = base64_encode_value(result);
61 result = (fragment & 0x00f) << 2;
62 /* fall through */
63
64 case step_C:
65 if (plainchar == plaintextend)
66 {
67 state_in->result = result;
68 state_in->step = step_C;
69 return (int)(codechar - code_out);
70 }
71 fragment = *plainchar++;
72 result |= (fragment & 0x0c0) >> 6;
73 *codechar++ = base64_encode_value(result);
74 result = (fragment & 0x03f) >> 0;
75 *codechar++ = base64_encode_value(result);
76
77 ++(state_in->stepcount);
78 }
79 }
80 /* control should not reach here */
81 return (int)(codechar - code_out);
82 }
83
base64_encode_blockend(char * code_out,base64_encodestate * state_in)84 int base64_encode_blockend(char* code_out, base64_encodestate* state_in)
85 {
86 char* codechar = code_out;
87
88 switch (state_in->step)
89 {
90 case step_B:
91 *codechar++ = base64_encode_value(state_in->result);
92 *codechar++ = '=';
93 *codechar++ = '=';
94 break;
95 case step_C:
96 *codechar++ = base64_encode_value(state_in->result);
97 *codechar++ = '=';
98 break;
99 case step_A:
100 break;
101 }
102 *codechar++ = '\n';
103
104 return (int)(codechar - code_out);
105 }
106
107