1 files changed, 154 insertions, 0 deletions
diff --git a/purgatory/printf.c b/purgatory/printf.c
new file mode 100644
index 0000000..9a78243
--- /dev/null
+++ b/purgatory/printf.c
@@ -0,0 +1,154 @@
+#include <stdarg.h>
+#include <limits.h>
+#include <stdint.h>
+#include <purgatory.h>
+#include <string.h>
+
+/*
+ * Output
+ * =============================================================================
+ */
+
+#define LONG_LONG_SHIFT  ((int)((sizeof(unsigned long long)*CHAR_BIT) - 4))
+#define LONG_SHIFT  ((int)((sizeof(unsigned long)*CHAR_BIT) - 4))
+#define INT_SHIFT   ((int)((sizeof(unsigned int)*CHAR_BIT) - 4))
+#define SHRT_SHIFT  ((int)((sizeof(unsigned short)*CHAR_BIT) - 4))
+#define CHAR_SHIFT  ((int)((sizeof(unsigned char)*CHAR_BIT) - 4))
+
+/**************************************************************************
+PRINTF and friends
+
+	Formats:
+		%x	- 4 bytes int (8 hex digits, lower case)
+		%X	- 4 bytes int (8 hex digits, upper case)
+		%lx     - 8 bytes long (16 hex digits, lower case)
+		%lX     - 8 bytes long (16 hex digits, upper case)
+		%hx	- 2 bytes int (4 hex digits, lower case)
+		%hX	- 2 bytes int (4 hex digits, upper case)
+		%hhx	- 1 byte int (2 hex digits, lower case)
+		%hhX	- 1 byte int (2 hex digits, upper case)
+			- optional # prefixes 0x or 0X
+		%d	- decimal int
+		%c	- char
+		%s	- string
+	Note: width specification not supported
+**************************************************************************/
+void vsprintf(char *buffer, const char *fmt, va_list args)
+{
+	char *p;
+	for ( ; *fmt != '\0'; ++fmt) {
+		if (*fmt != '%') {
+			if (buffer)
+				*buffer++ = *fmt;
+			else
+				putchar(*fmt);
+			continue;
+		}
+		if (*++fmt == 's') {
+			for(p = va_arg(args, char *); *p != '\0'; p++) 
+				if (buffer)
+					*buffer++ = *p;
+				else
+					putchar(*p);
+		}
+		else {	/* Length of item is bounded */
+			char tmp[40], *q = tmp;
+			int shift = INT_SHIFT;
+			if (*fmt == 'L') {
+				shift = LONG_LONG_SHIFT;
+				fmt++;
+			}
+			else if (*fmt == 'l') {
+				shift = LONG_SHIFT;
+				fmt++;
+			}
+			else if (*fmt == 'h') {
+				shift = SHRT_SHIFT;
+				fmt++;
+				if (*fmt == 'h') {
+					shift = CHAR_SHIFT;
+					fmt++;
+				}
+			}
+			
+			/*
+			 * Before each format q points to tmp buffer
+			 * After each format q points past end of item
+			 */
+			if ((*fmt | 0x20) == 'x') {
+				/* With x86 gcc, sizeof(long) == sizeof(int) */
+				unsigned long long h;
+				int ncase;
+				if (shift > LONG_SHIFT) {
+					h = va_arg(args, unsigned long long);
+				}
+				else if (shift > INT_SHIFT) {
+					h = va_arg(args, unsigned long);
+				} else {
+					h = va_arg(args, unsigned int);
+				}
+				ncase = (*fmt & 0x20);
+				for ( ; shift >= 0; shift -= 4)
+					*q++ = "0123456789ABCDEF"[(h >> shift) & 0xF] | ncase;
+			}
+			else if (*fmt == 'd') {
+				char *r;
+				long i;
+				if (shift > LONG_SHIFT) {
+					i = va_arg(args, long long);
+				}
+				else if (shift > INT_SHIFT) {
+					i = va_arg(args, long);
+				} else {
+					i = va_arg(args, int);
+				}
+				if (i < 0) {
+					*q++ = '-';
+					i = -i;
+				}
+				p = q;		/* save beginning of digits */
+				do {
+					*q++ = '0' + (i % 10);
+					i /= 10;
+				} while (i);
+				/* reverse digits, stop in middle */
+				r = q;		/* don't alter q */
+				while (--r > p) {
+					i = *r;
+					*r = *p;
+					*p++ = i;
+				}
+			}
+			else if (*fmt == 'c')
+				*q++ = va_arg(args, int);
+			else
+				*q++ = *fmt;
+			/* now output the saved string */
+			for (p = tmp; p < q; ++p)
+				if (buffer)
+					*buffer++ = *p;
+				else
+					putchar(*p);
+		}
+	}
+	if (buffer)
+		*buffer = '\0';
+}
+
+void sprintf(char *buffer, const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	vsprintf(buffer, fmt, args);
+	va_end(args);
+}
+
+void printf(const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	vsprintf(0, fmt, args);
+	va_end(args);
+}