somewhat optimized day 2. for fun

day2.c

@@ -249,10 +249,10 @@ no_len_change:
     return result;
 }
 
-#define RUN_TEST1 1
-#define RUN_PART1 1
+#define RUN_TEST1 0
+#define RUN_PART1 0
 #define RUN_TEST2 0
-#define RUN_PART2 0
+#define RUN_PART2 1
 
 #define TEST1_EXPECT 0x1227775554l
 #define TEST2_EXPECT 0x4174379265l

day2opt.c

@@ -0,0 +1,257 @@
+#include "lib.h"
+
+#define DBG 0
+
+static
+alignas(0x40) unsigned char input[] = {
+#embed "day2_input.txt"
+};
+
+struct id {
+    size_t len;
+    bcdint v;
+};
+
+static
+bcdint next_palindrome_len2(bcdint in) {
+    bcdint low  = in & 0xF;
+    bcdint high = in >> 4;
+
+    bcdint higher = high + 1;
+
+    bcdint high_pd =   0x11 * high;
+    bcdint higher_pd = 0x11 * higher;
+
+    return low > high ? higher_pd : high_pd;
+}
+
+static
+bcdint next_palindrome_len3(bcdint in) {
+    bcdint nib0  = in & 0xF;
+    bcdint nib1  = (in >> 4) & 0xF;
+    bcdint high  = in >> 8;
+
+    bcdint higher = high + 1;
+
+    bcdint high_pd =   0x111 * high;
+    bcdint higher_pd = 0x111 * higher;
+
+    if (nib1 < high) return high_pd;
+    return nib0 > high ? higher_pd : high_pd;
+}
+
+static
+bcdint next_palindrome_len4(bcdint in) {
+    bcdint nib0  = in & 0xF;
+    bcdint nib1  = (in >> 4) & 0xF;
+    bcdint nib2  = (in >> 8) & 0xF;
+    bcdint nib3  = in >> 12;
+
+    bcdint nib3er = nib3 + 1;
+
+    bcdint nib3_pd =   0x1111 * nib3;
+    bcdint nib3er_pd = 0x1111 * nib3er;
+
+    bcdint nib10 = in & 0xFF;
+    bcdint nib32 = in >> 8;
+
+    bcdint nib32er = bcdadd(nib32, 1);
+
+    bcdint nib32_pd   = 0x0101 * nib32;
+    bcdint nib32er_pd = 0x0101 * nib32er;
+
+    bcdint r = nib3er_pd;
+    if (nib3_pd > in) r = nib3_pd;
+    if (nib32er_pd > in) r = nib32er_pd;
+    if (nib32_pd > in) r = nib32_pd;
+
+    return r;
+}
+
+static
+bcdint next_palindrome_len6(bcdint in) {
+    bcdint nib0  = in & 0xF;
+    bcdint nib1  = (in >> 4)  & 0xF;
+    bcdint nib2  = (in >> 8)  & 0xF;
+    bcdint nib3  = (in >> 12) & 0xF;
+    bcdint nib4  = (in >> 16) & 0xF;
+    bcdint nib5  = in >> 20;
+
+    bcdint nib5er = nib5 + 1;
+
+    bcdint nib5_pd =   0x111111 * nib5;
+    bcdint nib5er_pd = 0x111111 * nib5er;
+
+    bcdint nib10 = in & 0xFF;
+    bcdint nib32 = (in >> 8) & 0xFF;
+    bcdint nib54 = in >> 16;
+
+    bcdint nib54er = bcdadd(nib54, 1);
+
+    bcdint nib54_pd   = 0x010101 * nib54;
+    bcdint nib54er_pd = 0x010101 * nib54er;
+
+    bcdint nib210 = in & 0xFFF;
+    bcdint nib543 = in >> 12;
+
+    bcdint nib543er = bcdadd(nib543, 1);
+
+    bcdint nib543_pd   = 0x001001 * nib543;
+    bcdint nib543er_pd = 0x001001 * nib543er;
+
+    bcdint r = nib5er_pd;
+    if (nib5_pd > in) r = MIN(r,nib5_pd);
+    if (nib54er_pd > in) r = MIN(r,nib54er_pd);
+    if (nib54_pd > in) r = MIN(r,nib54_pd);
+    if (nib543er_pd > in) r = MIN(r,nib543er_pd);
+    if (nib543_pd > in) r = MIN(r,nib543_pd);
+
+    return r;
+}
+
+static
+bcdint next_palindrome_len8(bcdint in) {
+    bcdint nib0  = in & 0xF;
+    bcdint nib1  = (in >> 4)  & 0xF;
+    bcdint nib2  = (in >> 8)  & 0xF;
+    bcdint nib3  = (in >> 12) & 0xF;
+    bcdint nib4  = (in >> 16) & 0xF;
+    bcdint nib5  = (in >> 20) & 0xF;
+    bcdint nib6  = (in >> 24) & 0xF;
+    bcdint nib7  = in >> 28;
+
+    bcdint nib7er = nib7 + 1;
+
+    bcdint nib7_pd =   0x11111111 * nib7;
+    bcdint nib7er_pd = 0x11111111 * nib7er;
+
+    bcdint nib10 = in & 0xFF;
+    bcdint nib32 = (in >> 8) & 0xFF;
+    bcdint nib54 = (in >> 16) & 0xFF;
+    bcdint nib76 = in >> 24;
+
+    bcdint nib76er = bcdadd(nib76, 1);
+
+    bcdint nib76_pd   = 0x01010101 * nib76;
+    bcdint nib76er_pd = 0x01010101 * nib76er;
+
+    bcdint nib3210 = in & 0xFFFF;
+    bcdint nib7654 = in >> 16;
+
+    bcdint nib7654er = bcdadd(nib7654, 1);
+
+    bcdint nib7654_pd   = 0x00010001 * nib7654;
+    bcdint nib7654er_pd = 0x00010001 * nib7654er;
+
+    bcdint r = nib7er_pd;
+    if (nib7_pd > in) r = MIN(r,nib7_pd);
+    if (nib76er_pd > in) r = MIN(r,nib76er_pd);
+    if (nib76_pd > in) r = MIN(r,nib76_pd);
+    if (nib7654er_pd > in) r = MIN(r,nib7654er_pd);
+    if (nib7654_pd > in) r = MIN(r,nib7654_pd);
+
+    return r;
+}
+
+static
+bcdint next_palindrome_part2(struct id s) {
+    if (s.len == 2)      return next_palindrome_len2(s.v);
+    else if (s.len == 3) return next_palindrome_len3(s.v);
+    else if (s.len == 4) return next_palindrome_len4(s.v);
+    else if (s.len == 6) return next_palindrome_len6(s.v);
+    else if (s.len == 8) return next_palindrome_len8(s.v);
+
+    unsigned len = s.len;
+    bcdint in = s.v;
+
+    bcdint best = -1;
+    for (unsigned i = 2; i <= len; i++) {
+        if (len % i == 0) {
+            unsigned high_shift = (len / i) * 4;
+
+            bcdint high = in >> (high_shift * (i - 1));
+
+            for (int j = i - 2; j >= 0; j--) {
+                bcdint low = (in >> (high_shift * (j))) & ((1 << high_shift) - 1);
+
+                if (low < high) {
+                    break;
+                } else if (low > high) {
+                    high = bcdadd(high, 1);
+                    break;
+                }
+            }
+
+            bcdint next = 0;
+            for (unsigned j = 0; j < i; j++) {
+                next |= high << (high_shift * j);
+            }
+
+            if (next < best) {
+                best = next;
+            }
+        }
+    }
+
+    return best;
+}
+
+static
+bcdint do_part2(size_t file_len, unsigned char file[file_len]) {
+    unsigned char *src = file;
+    bcdint result = 0;
+
+    alignas(0x40) struct id ranges[128];
+    size_t range_count = 0;
+
+    do {
+        unsigned char *tmp;
+        bcdint rs = grabbcd(src, &tmp);
+        ranges[range_count * 2 + 0] = (struct id) {
+            .len = tmp - src,
+            .v = rs
+        };
+        src = tmp + 1;
+
+        bcdint re = grabbcd(src, &tmp);
+        ranges[range_count * 2 + 1] = (struct id) {
+            .v = re
+        };
+        src = tmp + 1;
+
+        range_count++;
+    } while (src != &file[file_len]);
+
+    do {
+        range_count--;
+        struct id next = ranges[range_count * 2 + 0];
+        bcdint re = ranges[range_count * 2 + 1].v;
+        do {
+            if (next.len == 1) {
+                next = (struct id) { .len = 2, .v = 0x11 };
+            } else {
+                next.v = next_palindrome_part2(next);
+            }
+            if (next.v <= re) {
+                result = bcdadd(result, next.v);
+            }
+            bcdint tmp = bcdadd(next.v, 1);
+            for (bcdint chk = next.v; chk > 0; chk >>= 4) {
+                if ((chk & 0xF) != 9) goto no_len_change;
+            }
+            next.len++;
+            no_len_change:
+            next.v = tmp;
+        } while (next.v <= re);
+    } while (range_count);
+
+    return result;
+}
+
+void run() {
+    print("PART 2 RESULT: ");
+    printh(do_part2(countof(input), input));
+    print("\n");
+
+    exit_group(0);
+}

lib.h

@@ -27,6 +27,9 @@ void exit_group(uint64_t code) {
     for (;;);
 }
 
+#define MAX(x, y) (((x) > (y)) ? (x) : (y))
+#define MIN(x, y) (((x) < (y)) ? (x) : (y))
+
 #define xstr(s) str(s)
 #define str(s) #s