initial versioin

code/os/06-interrupts/printf.c

@@ -0,0 +1,138 @@
+#include "os.h"
+
+/*
+ * ref: https://github.com/cccriscv/mini-riscv-os/blob/master/05-Preemptive/lib.c
+ */
+
+static int _vsnprintf(char * out, size_t n, const char* s, va_list vl)
+{
+	int format = 0;
+	int longarg = 0;
+	size_t pos = 0;
+	for (; *s; s++) {
+		if (format) {
+			switch(*s) {
+			case 'l': {
+				longarg = 1;
+				break;
+			}
+			case 'p': {
+				longarg = 1;
+				if (out && pos < n) {
+					out[pos] = '0';
+				}
+				pos++;
+				if (out && pos < n) {
+					out[pos] = 'x';
+				}
+				pos++;
+			}
+			case 'x': {
+				long num = longarg ? va_arg(vl, long) : va_arg(vl, int);
+				int hexdigits = 2*(longarg ? sizeof(long) : sizeof(int))-1;
+				for(int i = hexdigits; i >= 0; i--) {
+					int d = (num >> (4*i)) & 0xF;
+					if (out && pos < n) {
+						out[pos] = (d < 10 ? '0'+d : 'a'+d-10);
+					}
+					pos++;
+				}
+				longarg = 0;
+				format = 0;
+				break;
+			}
+			case 'd': {
+				long num = longarg ? va_arg(vl, long) : va_arg(vl, int);
+				if (num < 0) {
+					num = -num;
+					if (out && pos < n) {
+						out[pos] = '-';
+					}
+					pos++;
+				}
+				long digits = 1;
+				for (long nn = num; nn /= 10; digits++);
+				for (int i = digits-1; i >= 0; i--) {
+					if (out && pos + i < n) {
+						out[pos + i] = '0' + (num % 10);
+					}
+					num /= 10;
+				}
+				pos += digits;
+				longarg = 0;
+				format = 0;
+				break;
+			}
+			case 's': {
+				const char* s2 = va_arg(vl, const char*);
+				while (*s2) {
+					if (out && pos < n) {
+						out[pos] = *s2;
+					}
+					pos++;
+					s2++;
+				}
+				longarg = 0;
+				format = 0;
+				break;
+			}
+			case 'c': {
+				if (out && pos < n) {
+					out[pos] = (char)va_arg(vl,int);
+				}
+				pos++;
+				longarg = 0;
+				format = 0;
+				break;
+			}
+			default:
+				break;
+			}
+		} else if (*s == '%') {
+			format = 1;
+		} else {
+			if (out && pos < n) {
+				out[pos] = *s;
+			}
+			pos++;
+		}
+    	}
+	if (out && pos < n) {
+		out[pos] = 0;
+	} else if (out && n) {
+		out[n-1] = 0;
+	}
+	return pos;
+}
+
+static char out_buf[1000]; // buffer for _vprintf()
+
+static int _vprintf(const char* s, va_list vl)
+{
+	int res = _vsnprintf(NULL, -1, s, vl);
+	if (res+1 >= sizeof(out_buf)) {
+		uart_puts("error: output string size overflow\n");
+		while(1) {}
+	}
+	_vsnprintf(out_buf, res + 1, s, vl);
+	uart_puts(out_buf);
+	return res;
+}
+
+int printf(const char* s, ...)
+{
+	int res = 0;
+	va_list vl;
+	va_start(vl, s);
+	res = _vprintf(s, vl);
+	va_end(vl);
+	return res;
+}
+
+void panic(char *s)
+{
+	printf("panic: ");
+	printf(s);
+	printf("\n");
+	while(1){};
+}