// clang-format off /* * The Minimal snprintf() implementation * * Copyright (c) 2013,2014 Michal Ludvig * 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 #include 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; } inline static void _putc(char **cursor, char *const buffer_end, char ch) { if (*cursor < buffer_end) *((*cursor)++) = ch; } inline static void _puts(char **cursor, char *const buffer_end, char *s, unsigned int len) { unsigned int i; if (buffer_end - *cursor < len) len = buffer_end - *cursor; /* Copy to buffer at cursor */ for (i = 0; i < len; i++) *((*cursor)++) = s[i]; } int mini_vsnprintf(char *buffer, unsigned int buffer_len, const char *fmt, va_list va) { char *pbuffer = buffer; char *const buffer_end = buffer + buffer_len; char bf[24]; char ch; while ((ch=*(fmt++))) { if (pbuffer + 1 >= buffer_end) break; if (ch!='%') { _putc(&pbuffer, buffer_end, ch); } 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(&pbuffer, buffer_end, bf, len); break; case 'x': case 'X': len = mini_itoa(va_arg(va, unsigned int), 16, (ch=='X'), 1, bf, zero_pad); _puts(&pbuffer, buffer_end, bf, len); break; case 'c' : _putc(&pbuffer, buffer_end, (char)(va_arg(va, int))); break; case 's' : ptr = va_arg(va, char*); _puts(&pbuffer, buffer_end, ptr, mini_strlen(ptr)); break; default: _putc(&pbuffer, buffer_end, ch); break; } } } end: if (pbuffer < buffer_end) *pbuffer = '\0'; else if (buffer_len > 0) buffer[buffer_len - 1] = '\0'; return pbuffer - 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; }