add minimal printf library

lib/print.c

@@ -0,0 +1,132 @@
+/* This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+/** printing utilities to replace the large printf from the standard library (code)
+ *  @file print.c
+ *  @author King Kévin <kingkevin@cuvoodoo.info>
+ *  @date 2017
+ */
+/* standard libraries */
+#include <stdint.h> // standard integer types
+#include <stdarg.h> // variadic utilities
+
+/* own libraries */
+#include "print.h" // printing utilities
+
+/** output \r\n (Carriage Return + Line Feed) for each \r, \n, \r\n, or \n\r for better terminal compatibility */
+#define CRLF 1
+
+void puts(const char* s)
+{
+	while (*s) { // stop at end of string
+#if CRLF
+		static char newline = 0; // to remember on which character we sent the newline
+
+		if ('\r' == *s || '\n' == *s) { // send CR+LF newline for most carriage return and line feed combination
+			if (0==newline || *s==newline) { // send newline only if not already send (and only once on \r\n or \n\r)
+					putc('\r'); // send CR
+					putc('\n'); // send LF
+					newline = *s; // remember on which character we sent the newline
+			}
+			s++; // go to next character
+			continue; // don't continue processing this character
+		} else {
+			newline = 0; // clear new line
+		}
+#endif
+		putc(*(s++)); // send character
+	}
+}
+
+static uint8_t print_unsigned(uint32_t u, uint8_t padding) {
+	char number[20] = {0}; // construct the number in reverse order (20 chars are required to store UINT64_MAX)
+	uint8_t digits = 0; // to count the number of digits
+	uint8_t pad = 0; // to count how much padding has been printed
+	do {
+		number[digits++] = '0'+(u%10); // store digit
+		u /= 10; // go to next digit
+	} while (u>0);
+	if (digits>sizeof(number)) { // prevent buffer underflow
+		return 0;
+	}
+	for (uint8_t zeros = digits; zeros<padding; zeros++) { // print padding 0's
+		putc('0'); // print 0
+		pad++; // count printed 0 padding
+	}
+	for (uint8_t digit = 0; digit < digits; digit++) { // go through all digits
+		putc(number[digits-digit-1]); // print digit (in reverse order)
+	}
+	return digits+pad; // return number of digits printed
+}
+
+uint32_t printf(const char *fmt, ...)
+{
+	uint32_t length = 0; // number of characters printed
+	uint8_t padding = 0; // number of padding 0's
+	va_list va; // variable argument list
+	va_start(va, fmt); // initialise variable argument list
+	while (*fmt) { // go through format string
+		if ('%'!=*fmt) { // check for format specifier prefix
+#if CRLF
+			static char newline = 0; // to remember on which character we sent the newline
+			if ('\r' == *fmt || '\n' == *fmt) { // send CR+LF newline for most carriage return and line feed combination
+				if (0==newline || *fmt==newline) { // send newline only if not already send (and only once on \r\n or \n\r)
+						putc('\r'); // send CR
+						putc('\n'); // send LF
+						newline = *fmt; // remember on which character we sent the newline
+						length += 2; // remember we printer the new line
+				}
+				fmt++; // go to next character
+				continue; // don't continue processing this character
+			} else {
+				newline = 0; // clear new line
+			}
+#endif
+			putc(*fmt++); // print character (no interpretation needed)
+			length++; // count printed character
+		} else {
+			fmt++; // go to format specifier
+			if (0==*fmt) { // end of string detected
+				goto end;
+			}
+			// check padding
+			if ('0'==*fmt) { // padding required
+				fmt++; // go to padding number
+				if (0==*fmt) { // end of string detected
+					goto end;
+				}
+				if (*fmt>='0' && *fmt<='9') {
+					padding = *fmt-'0';
+					fmt++; // go to format specifier
+					if (0==*fmt) { // end of string detected
+						goto end;
+					}
+				}
+			}
+			// check format specifier
+			switch (*fmt++) {
+				case 'u':
+					length += print_unsigned(va_arg(va,uint32_t), padding);
+					break;
+				default:
+					putc(*fmt++); // print character (unknown format specifier)
+					length++; // count printed character
+			}
+		}
+		padding = 0; // reset padding
+	}
+end:
+	va_end(va);
+	return length;
+}

lib/print.h

@@ -0,0 +1,24 @@
+/* This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+/** printing utilities to replace the large printf from the standard library (API)
+ *  @file print.h
+ *  @author King Kévin <kingkevin@cuvoodoo.info>
+ *  @date 2017
+ */
+#pragma once
+
+void putc(char c);
+void puts(const char* s);
+uint32_t printf(const char *fmt, ...);