base64.c
changeset 0 d7ee4e2ed49d
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/base64.c	Tue Dec 17 22:16:27 2013 -0500
@@ -0,0 +1,197 @@
+/*
+cdecoder.c - c source to a base64 decoding algorithm implementation
+
+This is part of the libb64 project, and has been placed in the public domain.
+For details, see http://sourceforge.net/projects/libb64
+*/
+
+#include "base64.h"
+
+int base64_decode_value(char value_in)
+{
+	static const char decoding[] = {62,-1,-1,-1,63,52,53,54,55,56,57,58,59,60,61,-1,-1,-1,-2,-1,-1,-1,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1,-1,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51};
+	static const char decoding_size = sizeof(decoding);
+	value_in -= 43;
+	if (value_in < 0 || value_in > decoding_size) return -1;
+	return decoding[(int)value_in];
+}
+
+void base64_init_decodestate(base64_decodestate* state_in)
+{
+	state_in->step = step_a;
+	state_in->plainchar = 0;
+}
+
+int base64_decode_block(const char* code_in, const int length_in, uint8_t* plaintext_out, base64_decodestate* state_in)
+{
+	const char* codechar = code_in;
+	uint8_t* plainchar = plaintext_out;
+	char fragment;
+	
+	*plainchar = state_in->plainchar;
+	
+	switch (state_in->step)
+	{
+		while (1)
+		{
+	case step_a:
+			do {
+				if (codechar == code_in+length_in)
+				{
+					state_in->step = step_a;
+					state_in->plainchar = *plainchar;
+					return plainchar - plaintext_out;
+				}
+				fragment = (char)base64_decode_value(*codechar++);
+			} while (fragment < 0);
+			*plainchar    = (fragment & 0x03f) << 2;
+	case step_b:
+			do {
+				if (codechar == code_in+length_in)
+				{
+					state_in->step = step_b;
+					state_in->plainchar = *plainchar;
+					return plainchar - plaintext_out;
+				}
+				fragment = (char)base64_decode_value(*codechar++);
+			} while (fragment < 0);
+			*plainchar++ |= (fragment & 0x030) >> 4;
+			*plainchar    = (fragment & 0x00f) << 4;
+	case step_c:
+			do {
+				if (codechar == code_in+length_in)
+				{
+					state_in->step = step_c;
+					state_in->plainchar = *plainchar;
+					return plainchar - plaintext_out;
+				}
+				fragment = (char)base64_decode_value(*codechar++);
+			} while (fragment < 0);
+			*plainchar++ |= (fragment & 0x03c) >> 2;
+			*plainchar    = (fragment & 0x003) << 6;
+	case step_d:
+			do {
+				if (codechar == code_in+length_in)
+				{
+					state_in->step = step_d;
+					state_in->plainchar = *plainchar;
+					return plainchar - plaintext_out;
+				}
+				fragment = (char)base64_decode_value(*codechar++);
+			} while (fragment < 0);
+			*plainchar++   |= (fragment & 0x03f);
+		}
+	}
+	/* control should not reach here */
+	return plainchar - plaintext_out;
+}
+
+/*
+cencoder.c - c source to a base64 encoding algorithm implementation
+
+This is part of the libb64 project, and has been placed in the public domain.
+For details, see http://sourceforge.net/projects/libb64
+*/
+
+const int CHARS_PER_LINE = 72;
+
+void base64_init_encodestate(base64_encodestate* state_in)
+{
+	state_in->step = step_A;
+	state_in->result = 0;
+	state_in->stepcount = 0;
+}
+
+char base64_encode_value(char value_in)
+{
+	static const char* encoding = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+	if (value_in > 63) return '=';
+	return encoding[(int)value_in];
+}
+
+int base64_encode_block(const uint8_t* plaintext_in, int length_in, char* code_out, base64_encodestate* state_in)
+{
+	const uint8_t* plainchar = plaintext_in;
+	const uint8_t* const plaintextend = plaintext_in + length_in;
+	char* codechar = code_out;
+	char result;
+	uint8_t fragment;
+	
+	result = state_in->result;
+	
+	switch (state_in->step)
+	{
+		while (1)
+		{
+	case step_A:
+			if (plainchar == plaintextend)
+			{
+				state_in->result = result;
+				state_in->step = step_A;
+				return codechar - code_out;
+			}
+			fragment = *plainchar++;
+			result = (fragment & 0x0fc) >> 2;
+			*codechar++ = base64_encode_value(result);
+			result = (fragment & 0x003) << 4;
+	case step_B:
+			if (plainchar == plaintextend)
+			{
+				state_in->result = result;
+				state_in->step = step_B;
+				return codechar - code_out;
+			}
+			fragment = *plainchar++;
+			result |= (fragment & 0x0f0) >> 4;
+			*codechar++ = base64_encode_value(result);
+			result = (fragment & 0x00f) << 2;
+	case step_C:
+			if (plainchar == plaintextend)
+			{
+				state_in->result = result;
+				state_in->step = step_C;
+				return codechar - code_out;
+			}
+			fragment = *plainchar++;
+			result |= (fragment & 0x0c0) >> 6;
+			*codechar++ = base64_encode_value(result);
+			result  = (fragment & 0x03f) >> 0;
+			*codechar++ = base64_encode_value(result);
+			
+			++(state_in->stepcount);
+			if (state_in->stepcount == CHARS_PER_LINE/4)
+			{
+				*codechar++ = '\n';
+				state_in->stepcount = 0;
+			}
+		}
+	}
+	/* control should not reach here */
+	return codechar - code_out;
+}
+
+int base64_encode_blockend(char* code_out, base64_encodestate* state_in)
+{
+	char* codechar = code_out;
+	
+	switch (state_in->step)
+	{
+	case step_B:
+		*codechar++ = base64_encode_value(state_in->result);
+		*codechar++ = '=';
+		*codechar++ = '=';
+		break;
+	case step_C:
+		*codechar++ = base64_encode_value(state_in->result);
+		*codechar++ = '=';
+		break;
+	case step_A:
+		break;
+	}
+	*codechar++ = '\n';
+	
+	return codechar - code_out;
+}
+
+// end of base64.c ...
+