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/* Copyright 2022 The Chromium OS Authors.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
/* Yet another from scratch implementation of base64 encoding. */
#include "base64.h"
#include "common.h"
#include "console.h"
/*
* Translation Table as described in RFC1113
*/
static const char cb64[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
/* Number of bytes converted into the output block of characters. */
#define BASE64_BYTE_SIZE 3
/* Number of characters in a single encoded block. */
#define BASE64_CHAR_SIZE 4
/*
* encodeblock
*
* encode up to 3 bytes 6-bit characters, pad output with '=' if input is
* shorter than 3 bytes.
*
* @param in: pointer to the input bytes
* @param out: pointer to the output, guaranteed to be 4 bytes long.
* @param len: number of input bytes to process, guaranteed to be in 1..3
* range.
*/
static void encodeblock(const uint8_t *in, uint8_t *out, size_t len)
{
uint32_t input;
int i;
int limit;
/* Place input bytes into a 32 bit value in big endian format. */
input = 0;
for (i = 0; i < len; i++)
((uint8_t *)&input)[3 - i] = in[i];
/*
* Map each 6 bit quantity of the input into an output character, make
* sure partial bit quantities are mapped too in case input is shorter
* than 3 bytes.
*/
limit = ((len * 8) + 7) / 6;
for (i = 0; i < limit; i++) {
int index = (input >> (26 - i * 6)) & 0x3f;
out[i] = cb64[index];
}
while (i < BASE64_CHAR_SIZE)
out[i++] = '=';
}
/* Pass one output character to the caller. */
static void printit(char c, void (*f)(char c))
{
if (f)
f(c);
else
ccprintf("%c", c);
}
#define LINE_SIZE 64
void base64_encode_to_console(const uint8_t *data, size_t size,
void (*func)(char c))
{
uint8_t out[4];
int blocksout;
blocksout = 0;
while (size) {
int i;
int in_length;
if (size > BASE64_BYTE_SIZE)
in_length = BASE64_BYTE_SIZE;
else
in_length = size;
encodeblock(data, out, in_length);
for (i = 0; i < sizeof(out); i++)
printit(out[i], func);
blocksout++;
data += in_length;
size -= in_length;
if (blocksout >= (LINE_SIZE / BASE64_CHAR_SIZE)) {
printit('\n', func);
blocksout = 0;
if (!func)
cflush();
}
}
if (blocksout)
printit('\n', func);
}
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