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Diffstat (limited to 'fw/mini-printf.c')
| -rw-r--r-- | fw/mini-printf.c | 208 |
1 files changed, 208 insertions, 0 deletions
diff --git a/fw/mini-printf.c b/fw/mini-printf.c new file mode 100644 index 0000000..53cfe99 --- /dev/null +++ b/fw/mini-printf.c @@ -0,0 +1,208 @@ +/* + * 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; +} |