/*

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 ...