arduino-esp32/cores/esp32/libb64/cdecode.c
Lucas Saavedra Vaz da5c6ab9ae
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Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>
Co-authored-by: Rodrigo Garcia <rodrigo.garcia@espressif.com>
2024-04-15 19:40:56 +03:00

102 lines
3.7 KiB
C

/*
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 "cdecode.h"
#include <stdint.h>
static int base64_decode_value_signed(int8_t value_in) {
static const int8_t 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 int8_t 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;
}
static int base64_decode_block_signed(const int8_t* code_in, const int length_in, int8_t* plaintext_out, base64_decodestate* state_in) {
const int8_t* codechar = code_in;
int8_t* plainchar = plaintext_out;
int8_t 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 = (int8_t)base64_decode_value_signed(*codechar++);
} while (fragment < 0);
*plainchar = (fragment & 0x03f) << 2;
// fall through
case step_b:
do {
if (codechar == code_in + length_in) {
state_in->step = step_b;
state_in->plainchar = *plainchar;
return plainchar - plaintext_out;
}
fragment = (int8_t)base64_decode_value_signed(*codechar++);
} while (fragment < 0);
*plainchar++ |= (fragment & 0x030) >> 4;
*plainchar = (fragment & 0x00f) << 4;
// fall through
case step_c:
do {
if (codechar == code_in + length_in) {
state_in->step = step_c;
state_in->plainchar = *plainchar;
return plainchar - plaintext_out;
}
fragment = (int8_t)base64_decode_value_signed(*codechar++);
} while (fragment < 0);
*plainchar++ |= (fragment & 0x03c) >> 2;
*plainchar = (fragment & 0x003) << 6;
// fall through
case step_d:
do {
if (codechar == code_in + length_in) {
state_in->step = step_d;
state_in->plainchar = *plainchar;
return plainchar - plaintext_out;
}
fragment = (int8_t)base64_decode_value_signed(*codechar++);
} while (fragment < 0);
*plainchar++ |= (fragment & 0x03f);
}
}
/* control should not reach here */
return plainchar - plaintext_out;
}
static int base64_decode_chars_signed(const int8_t* code_in, const int length_in, int8_t* plaintext_out) {
base64_decodestate _state;
base64_init_decodestate(&_state);
int len = base64_decode_block_signed(code_in, length_in, plaintext_out, &_state);
if (len > 0) plaintext_out[len] = 0;
return len;
}
int base64_decode_value(char value_in) {
return base64_decode_value_signed(*((int8_t*)&value_in));
}
int base64_decode_block(const char* code_in, const int length_in, char* plaintext_out, base64_decodestate* state_in) {
return base64_decode_block_signed((int8_t*)code_in, length_in, (int8_t*)plaintext_out, state_in);
}
int base64_decode_chars(const char* code_in, const int length_in, char* plaintext_out) {
return base64_decode_chars_signed((int8_t*)code_in, length_in, (int8_t*)plaintext_out);
}