sample-code: Expand the capabilities of the sample code

sample-code/hex.cl

@@ -1,12 +1,31 @@
-pub fn hex(mut n: u64) {
-    let hex_lut = [
+//! Formats numbers in hexadecimal, octal, or binary
+mod math;
+
+// TODO: casting and/or conversion
+const HEX_LUT: Array = [
     '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f',
-    ];
-    for xd in 0..16 {
-        let n = n >> (15 - xd) * 4;
-        if n != 0 {
-            print(hex_lut[n & 0xf])
+];
+
+pub fn hex(n: u64) {
+    let out = "0x";
+    for xd in min(count_leading_zeroes(n) / 4, 15)..16 {
+        out += HEX_LUT[(n >> (15 - xd) * 4) & 0xf]
     }
-    }
-    println()
+    out
+}
+
+pub fn oct(n: u64) {
+    let out = "0o";
+    for xd in min((count_leading_zeroes(n) + 2) / 3, 21)..22 {
+        out += HEX_LUT[(n >> max(63 - (3 * xd), 0)) & 7]
+    }
+    out
+}
+
+pub fn bin(n: u64) {
+    let out = "0b";
+    for xd in min(count_leading_zeroes(n), 63)..64 {
+        out += HEX_LUT[(n >> 63 - xd) & 1]
+    }
+    out
 }

sample-code/math.cl

@@ -0,0 +1,36 @@
+//! Useful math functions
+
+pub fn max(a: T, b: T) -> T {
+    (if a < b { b } else { a })
+}
+
+pub fn min(a: T, b: T) -> T {
+    (if a > b { b } else { a })
+}
+
+pub fn count_leading_zeroes(n: u64) -> u64 {
+    let mut xd = 64;
+    if n < 0 {
+        return 0;
+    }
+    while n != 0 {
+        xd -= 1;
+        n >>= 1;
+    }
+    xd
+}
+
+pub fn count_trailing_zeroes(n: u64) -> u64 {
+    let mut xd = 0;
+    if n == 0 {
+        64
+    } else if n < 0 {
+        0
+    } else {
+        while n & 1 == 0 {
+            xd += 1;
+            n >>= 1;
+        }
+        xd
+    }
+}