64-bit integer routines

[originally from svn r937]

int64.c

@@ -0,0 +1,66 @@
+/*
+ * Handling of the int64 and uint64 types. Done in 32-bit integers,
+ * for (pre-C99) portability. Hopefully once C99 becomes widespread
+ * we can kiss this lot goodbye...
+ */
+
+#include <assert.h>
+
+typedef struct {
+    unsigned long hi, lo;
+} uint64, int64;
+
+uint64 uint64_div10(uint64 x, int *remainder) {
+    uint64 y;
+    int rem, r2;
+    y.hi = x.hi / 10;
+    y.lo = x.lo / 10;
+    rem = x.lo % 10;
+    /*
+     * Now we have to add in the remainder left over from x.hi.
+     */
+    r2 = x.hi % 10;
+    y.lo += r2 * 2 * (0x80000000 / 10);
+    rem += r2 * 2 * (0x80000000 % 10);
+    y.lo += rem / 10;
+    rem %= 10;
+
+    if (remainder)
+	*remainder = rem;
+    return y;
+}
+
+void uint64_decimal(uint64 x, char *buffer) {
+    char buf[20];
+    int start = 20;
+    int d;
+
+    while (x.hi || x.lo) {
+	x = uint64_div10(x, &d);
+	assert(start > 0);
+	buf[--start] = d + '0';
+    }
+
+    memcpy(buffer, buf+start, sizeof(buf)-start);
+    buffer[sizeof(buf)-start] = '\0';
+}
+
+uint64 uint64_make(unsigned long hi, unsigned long lo) {
+    uint64 y;
+    y.hi = hi;
+    y.lo = lo;
+    return y;
+}
+
+uint64 uint64_add(uint64 x, uint64 y) {
+    x.lo += y.lo;
+    x.hi += y.hi + (x.lo < y.lo ? 1 : 0);
+    return x;
+}
+
+uint64 uint64_add32(uint64 x, unsigned long y) {
+    uint64 yy;
+    yy.hi = 0;
+    yy.lo = y;
+    return uint64_add(x, yy);
+}

int64.h

@@ -0,0 +1,18 @@
+/*
+ * Header for int64.c.
+ */
+
+#ifndef PUTTY_INT64_H
+#define PUTTY_INT64_H
+
+typedef struct {
+    unsigned long hi, lo;
+} uint64, int64;
+
+uint64 uint64_div10(uint64 x, int *remainder);
+void uint64_decimal(uint64 x, char *buffer);
+uint64 uint64_make(unsigned long hi, unsigned long lo);
+uint64 uint64_add(uint64 x, uint64 y);
+uint64 uint64_add32(uint64 x, unsigned long y);
+
+#endif