From 007234f7b2c56683347451165702e98c42648a22 Mon Sep 17 00:00:00 2001
From: Sijmen Schoon <me@sijmenschoon.nl>
Date: Tue, 18 Dec 2018 15:07:03 +0100
Subject: [PATCH] Clean up day 16

---
 Day16/Day16B.c | 75 ++++++++++++++++++++++++++++----------------------
 1 file changed, 42 insertions(+), 33 deletions(-)

diff --git a/Day16/Day16B.c b/Day16/Day16B.c
index 3ff0515..cdd5c7e 100644
--- a/Day16/Day16B.c
+++ b/Day16/Day16B.c
@@ -16,44 +16,32 @@ typedef struct {
 } Sample;
 
 enum {
-    ADDR, ADDI, MULR, MULI,
-    BANR, BANI, BORR, BORI,
-    SETR, SETI, GTIR, GTRI,
-    GTRR, EQIR, EQRI, EQRR,
+    ADDR, ADDI, MULR, MULI, BANR, BANI, BORR, BORI,
+    SETR, SETI, GTIR, GTRI, GTRR, EQIR, EQRI, EQRR,
 };
 
+#ifdef DEBUG
 const char *names[] = {
-    "addr", "addi", "mulr", "muli",
-    "banr", "bani", "borr", "bori",
-    "setr", "seti", "gtir", "gtri",
-    "gtrr", "eqir", "eqri", "eqrr",
-};
-
-uint16_t table[16] = {
-    0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
-    0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
-    0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
-    0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
+    "addr", "addi", "mulr", "muli", "banr", "bani", "borr", "bori",
+    "setr", "seti", "gtir", "gtri", "gtrr", "eqir", "eqri", "eqrr",
 };
+#endif
 
 int opcodes[16];
 
 int sample_read(Sample *s, FILE *file) {
     int read = 0;
 
-    read =
-        fscanf(file, "Before: [%u, %u, %u, %u]\n",
-               &s->before[0], &s->before[1], &s->before[2], &s->before[3]);
+    read = fscanf(file, "Before: [%u, %u, %u, %u]\n",
+                  &s->before[0], &s->before[1], &s->before[2], &s->before[3]);
     if (read != 4) return 0;
 
     Instruction *i = &s->instruction;
-    read = fscanf(file, "%" SCNu8 " %u %u %u\n",
-                   &i->opcode, &i->a, &i->b, &i->c);
+    read = fscanf(file, "%" SCNu8 " %u %u %u\n", &i->opcode, &i->a, &i->b, &i->c);
     if (read != 4) return 0;
 
-    read =
-        fscanf(file, "After: [%u, %u, %u, %u]\n\n",
-               &s->after[0], &s->after[1], &s->after[2], &s->after[3]);
+    read = fscanf(file, "After: [%u, %u, %u, %u]\n\n",
+                  &s->after[0], &s->after[1], &s->after[2], &s->after[3]);
     if (read != 4) return 0;
 
     return 1;
@@ -63,25 +51,32 @@ uint16_t sample_possible_opcodes(const Sample s) {
     uint16_t possible_opcodes = 0;
 
     Instruction i = s.instruction;
+
     // Addition
     if (s.after[i.c] == s.before[i.a] + s.before[i.b])    possible_opcodes |= 1 << ADDR;
     if (s.after[i.c] == s.before[i.a] + i.b)              possible_opcodes |= 1 << ADDI;
+
     // Multiplication
     if (s.after[i.c] == s.before[i.a] * s.before[i.b])    possible_opcodes |= 1 << MULR;
     if (s.after[i.c] == s.before[i.a] * i.b)              possible_opcodes |= 1 << MULI;
+
     // Bitwise AND
     if (s.after[i.c] == (s.before[i.a] & s.before[i.b]))  possible_opcodes |= 1 << BANR;
     if (s.after[i.c] == (s.before[i.a] & i.b))            possible_opcodes |= 1 << BANI;
+
     // Bitwise OR
     if (s.after[i.c] == (s.before[i.a] | s.before[i.b]))  possible_opcodes |= 1 << BORR;
     if (s.after[i.c] == (s.before[i.a] | i.b))            possible_opcodes |= 1 << BORI;
+
     // Assignment
     if (s.after[i.c] == s.before[i.a])                    possible_opcodes |= 1 << SETR;
     if (s.after[i.c] == i.a)                              possible_opcodes |= 1 << SETI;
+
     // Greater-than testing
     if (s.after[i.c] == (i.a > s.before[i.b]))            possible_opcodes |= 1 << GTIR;
     if (s.after[i.c] == (s.before[i.a] > i.b))            possible_opcodes |= 1 << GTRI;
     if (s.after[i.c] == (s.before[i.a] > s.before[i.b]))  possible_opcodes |= 1 << GTRR;
+
     // Equality testing
     if (s.after[i.c] == (i.a == s.before[i.b]))           possible_opcodes |= 1 << EQIR;
     if (s.after[i.c] == (s.before[i.a] == i.b))           possible_opcodes |= 1 << EQRI;
@@ -101,8 +96,19 @@ int bits_set(uint16_t n) {
     return bit;
 }
 
-void find_opcodes() {
+void find_opcodes(FILE *file) {
     int unknown = 16;
+    uint16_t table[16] = {
+        0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
+        0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
+    };
+
+    Sample sample;
+    while (sample_read(&sample, file)) {
+        uint16_t possible_opcodes = sample_possible_opcodes(sample);
+        table[sample.instruction.opcode] &= possible_opcodes;
+    }
+
     while (unknown > 0) {
         for (int opcode = 0; opcode < 16; opcode++) {
             int bit = bits_set(table[opcode]);
@@ -117,9 +123,10 @@ void find_opcodes() {
         }
     }
 
-    for (int i = 0; i < 16; i++) {
+#ifdef DEBUG
+    for (int i = 0; i < 16; i++)
         printf("%d: %s\n", i, names[opcodes[i]]);
-    }
+#endif
 }
 
 int instruction_read(Instruction *i, FILE *file) {
@@ -170,25 +177,27 @@ int main(int argc, char **argv) {
     }
 
     FILE *file = fopen(argv[1], "r");
-    Sample sample = {0};
-
-    while (sample_read(&sample, file)) {
-        uint16_t possible_opcodes = sample_possible_opcodes(sample);
-        table[sample.instruction.opcode] &= possible_opcodes;
-    }
-    find_opcodes();
+    find_opcodes(file);
 
     uint32_t registers[4] = {0};
     Instruction instruction = {0};
     while (instruction_read(&instruction, file)) {
+#ifdef DEBUG
         const char *name = names[opcodes[instruction.opcode]];
         printf("opcode: %2d (%s), a: %d, b: %d, c: %d\n", instruction.opcode,
                name, instruction.a, instruction.b, instruction.c);
+#endif
+
         instruction_execute(&instruction, registers);
+
+#ifdef DEBUG
         printf("registers: %d %d %d %d\n", registers[0], registers[1],
                registers[2], registers[3]);
+#endif
     }
 
     fclose(file);
+
+    printf("%d\n", registers[0]);
     return EXIT_SUCCESS;
 }