summaryrefslogtreecommitdiff
path: root/src/new32.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/new32.c')
-rw-r--r--src/new32.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/src/new32.c b/src/new32.c
new file mode 100644
index 0000000..9136115
--- /dev/null
+++ b/src/new32.c
@@ -0,0 +1,24 @@
+#include <stdint.h>
+
+static const unsigned int divtab[244] = {
+ [1] = 0xffff + 1l,
+ [3] = 0x5555 + 1l,
+ [9] = 0x1c71 + 1l,
+ [27] = 0x097b + 1l,
+ [81] = 0x0329 + 1l,
+ [243] = 0x010d + 1l
+};
+
+#define FASTDIV(n, C) (((n) * (C)) >> 16)
+#define FASTMOD(n, d, C) ((n) - (d) * FASTDIV((n), (C)))
+
+int new32(int i, int x, int y)
+{
+ int A, B, C;
+
+ A = FASTDIV(i, divtab[y]);
+ B = FASTMOD(A, 3, divtab[3]);
+ C = FASTMOD(A + x, 3, divtab[3]);
+
+ return i + (C - B) * y;
+}