ternary

commit f2e4b139be9569a14a1262d161062b1984f691e4
Author: Robert Russell <robert@rr3.xyz>
Date:   Wed,  1 Oct 2025 22:09:19 -0700

Initial commit

Diffstat:
A
.gitignore
 | 
1
+
A
Makefile
 | 
2
++
A
main.c
 | 
58
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

3 files changed, 61 insertions(+), 0 deletions(-)
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1 @@
+main
diff --git a/Makefile b/Makefile
@@ -0,0 +1,2 @@
+main: main.c
+	gcc -Wall -o $@ main.c
diff --git a/main.c b/main.c
@@ -0,0 +1,58 @@
+#include <rcx/all.h>
+#include <stdio.h>
+#include <string.h>
+
+#define LOWER 0x5555555555555555ul
+#define UPPER 0xaaaaaaaaaaaaaaaaul
+
+typedef u64 ut32;
+
+inline u64
+carry_out(u64 x, u64 y, u64 s) {
+	return (x & y) | ((x ^ y) & ~s);
+}
+
+ut32
+ut32_add_tritwise(ut32 x, ut32 y) {
+	u64 sl = (x & LOWER) + (y & LOWER) + LOWER;
+	u64 sh = (x ^ y) & UPPER;
+	u64 s = sh ^ sl;
+	u64 d = (~carry_out(x, y, s) & UPPER) >> 1;
+	return s - d;
+}
+
+ut32
+ut32_add(ut32 x, ut32 y) {
+	u64 s = x + y + LOWER;
+	u64 d = (~carry_out(x, y, s) & UPPER) >> 1;
+	return s - d;
+}
+
+void
+ut32_sprint(char *dst, ut32 x) {
+	static char trit[4] = "012?";
+
+	char buf[33];
+	buf[32] = '\0';
+
+	usize i = 32;
+	while (i > 0) {
+		buf[--i] = trit[x & 3];
+		x >>= 2;
+		if (x == 0) break;
+	}
+	strcpy(dst, buf + i);
+}
+
+int
+main(void) {
+	char buf[33];
+
+	ut32 x = 0b00011010;
+	ut32 y = 0b01100001;
+	ut32 s = ut32_add(x, y);
+
+	ut32_sprint(buf, x); printf("x: %9s\n", buf);
+	ut32_sprint(buf, y); printf("y: %9s\n", buf);
+	ut32_sprint(buf, s); printf("s: %9s\n", buf);
+}