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/*
* The Minimal snprintf() implementation
*
* Copyright (c) 2013,2014 Michal Ludvig <michal@logix.cz>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the auhor nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* ----
*
* This is a minimal snprintf() implementation optimised
* for embedded systems with a very limited program memory.
* mini_snprintf() doesn't support _all_ the formatting
* the glibc does but on the other hand is a lot smaller.
* Here are some numbers from my STM32 project (.bin file size):
* no snprintf(): 10768 bytes
* mini snprintf(): 11420 bytes (+ 652 bytes)
* glibc snprintf(): 34860 bytes (+24092 bytes)
* Wasting nearly 24kB of memory just for snprintf() on
* a chip with 32kB flash is crazy. Use mini_snprintf() instead.
*
*/
#include "mini-printf.h"
static unsigned int
mini_strlen(const char *s)
{
unsigned int len = 0;
while (s[len] != '\0') len++;
return len;
}
static unsigned int
mini_itoa(int value, unsigned int radix, unsigned int uppercase, unsigned int unsig,
char *buffer, unsigned int zero_pad)
{
char *pbuffer = buffer;
int negative = 0;
unsigned int i, len;
/* No support for unusual radixes. */
if (radix > 16)
return 0;
if (value < 0 && !unsig) {
negative = 1;
value = -value;
}
/* This builds the string back to front ... */
do {
int digit = value % radix;
*(pbuffer++) = (digit < 10 ? '0' + digit : (uppercase ? 'A' : 'a') + digit - 10);
value /= radix;
} while (value > 0);
for (i = (pbuffer - buffer); i < zero_pad; i++)
*(pbuffer++) = '0';
if (negative)
*(pbuffer++) = '-';
*(pbuffer) = '\0';
/* ... now we reverse it (could do it recursively but will
* conserve the stack space) */
len = (pbuffer - buffer);
for (i = 0; i < len / 2; i++) {
char j = buffer[i];
buffer[i] = buffer[len-i-1];
buffer[len-i-1] = j;
}
return len;
}
struct mini_buff {
char *buffer, *pbuffer;
unsigned int buffer_len;
};
static int
_putc(int ch, struct mini_buff *b)
{
if ((unsigned int)((b->pbuffer - b->buffer) + 1) >= b->buffer_len)
return 0;
*(b->pbuffer++) = ch;
*(b->pbuffer) = '\0';
return 1;
}
static int
_puts(char *s, unsigned int len, struct mini_buff *b)
{
unsigned int i;
if (b->buffer_len - (b->pbuffer - b->buffer) - 1 < len)
len = b->buffer_len - (b->pbuffer - b->buffer) - 1;
/* Copy to buffer */
for (i = 0; i < len; i++)
*(b->pbuffer++) = s[i];
*(b->pbuffer) = '\0';
return len;
}
int
mini_vsnprintf(char *buffer, unsigned int buffer_len, const char *fmt, va_list va)
{
struct mini_buff b;
char bf[24];
char ch;
b.buffer = buffer;
b.pbuffer = buffer;
b.buffer_len = buffer_len;
while ((ch=*(fmt++))) {
if ((unsigned int)((b.pbuffer - b.buffer) + 1) >= b.buffer_len)
break;
if (ch!='%')
_putc(ch, &b);
else {
char zero_pad = 0;
char *ptr;
unsigned int len;
ch=*(fmt++);
/* Zero padding requested */
if (ch=='0') {
ch=*(fmt++);
if (ch == '\0')
goto end;
if (ch >= '0' && ch <= '9')
zero_pad = ch - '0';
ch=*(fmt++);
}
switch (ch) {
case 0:
goto end;
case 'u':
case 'd':
len = mini_itoa(va_arg(va, unsigned int), 10, 0, (ch=='u'), bf, zero_pad);
_puts(bf, len, &b);
break;
case 'x':
case 'X':
len = mini_itoa(va_arg(va, unsigned int), 16, (ch=='X'), 1, bf, zero_pad);
_puts(bf, len, &b);
break;
case 'c' :
_putc((char)(va_arg(va, int)), &b);
break;
case 's' :
ptr = va_arg(va, char*);
_puts(ptr, mini_strlen(ptr), &b);
break;
default:
_putc(ch, &b);
break;
}
}
}
end:
return b.pbuffer - b.buffer;
}
int
mini_snprintf(char* buffer, unsigned int buffer_len, const char *fmt, ...)
{
int ret;
va_list va;
va_start(va, fmt);
ret = mini_vsnprintf(buffer, buffer_len, fmt, va);
va_end(va);
return ret;
}
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