Day 3 Part 2 (Linux Kernel Module)

day3/answer2

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+75847567

day3/aoc2023d3p2.c

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+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/ctype.h>
+
+#define MODULE_NAME "aoc2023d3p2"
+MODULE_AUTHOR("logan2611");
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_DESCRIPTION("Advent of Code 2023 Day 3 Part 2 (The Linux Kernel Module)");
+MODULE_VERSION("0.1");
+
+const int length = 140; // Number of lines
+//const int length = 10; // Number of lines
+const int width = length + 1; // Width of lines (including newline, carriage return or null terminator)
+
+// Parameter that specifies the input file
+static char *path = "/tmp/input";
+module_param(path, charp, S_IRUGO);
+MODULE_PARM_DESC(path, "The path to the data input.");
+
+static ssize_t read_input(struct file *file, loff_t pos, size_t n, char *buffer) {
+    ssize_t bytes_read;
+
+    bytes_read = kernel_read(file, buffer, n, &pos);
+    if (bytes_read < 0) {
+        pr_err("%s: Error reading file: %zd\n", MODULE_NAME, bytes_read);
+    }
+
+    return bytes_read;
+}
+
+static void make_num_string(char *input, char *output, int head, int tail) {
+    memcpy(output, input + head, tail+1-head);
+}
+
+static int atoi(char *input) {
+    int ret;
+    int err = kstrtoint(input, 10, &ret);
+    if (err < 0) {
+        //pr_err("%s: Failed to convert string to number: \"%d\"\n", MODULE_NAME, err);
+        return 0;
+    }
+
+    return ret;
+}
+
+
+static int find_head_number(char *input, int pos) {
+    while(isdigit(input[pos]) && pos >= 0) {
+        //pr_info("%s: Scanning head: %c (%d)\n", MODULE_NAME, input[pos], pos);
+        pos--;
+    }
+    //pr_info("%s: Found head: %c (%d)\n", MODULE_NAME, input[pos], pos);
+    return pos + 1;
+}
+
+static int find_tail_number(char *input, int head) {
+    while(isdigit(input[head])) {
+        //pr_info("%s: Scanning tail: %c (%d)\n", MODULE_NAME, input[head], head);
+        head++;
+    }
+    //pr_info("%s: Found tail: %c (%d)\n", MODULE_NAME, input[head], head);
+    return head - 1;
+}
+
+static int find_adjacent_numbers(char *top, char *middle, char *bottom, int offset) {
+    int adjacent = 0;
+    int prod = 1;
+
+    int topskip = 0;
+    int midskip = 0;
+    int botskip = 0;
+
+    for(int pos = offset-1; pos <= offset+1; pos++) {
+        //pr_info("%s: Scanning position %d\n", MODULE_NAME, pos);
+        if(isdigit(top[pos]) && pos > topskip) {
+            int head = find_head_number(top, pos);
+            int tail = find_tail_number(top, head);
+
+
+            char numstr[8] = {0};
+            make_num_string(top, numstr, head, tail);
+
+            prod *= atoi(numstr);
+            adjacent++;
+            topskip = tail;
+            pr_info("%s: Found adjacent number top: %d %d-%d v:%d\n", MODULE_NAME, pos, head, tail, atoi(numstr));
+        }
+
+        if(isdigit(middle[pos]) && pos > midskip) {
+            int head = find_head_number(middle, pos);
+            int tail = find_tail_number(middle, head);
+
+            char numstr[8] = {0};
+            make_num_string(middle, numstr, head, tail);
+
+            prod *= atoi(numstr);
+            adjacent++;
+            midskip = tail;
+            pr_info("%s: Found adjacent number mid: %d %d-%d v:%d\n", MODULE_NAME, pos, head, tail, atoi(numstr));
+        }
+
+        if(isdigit(bottom[pos]) && pos > botskip) {
+            int head = find_head_number(bottom, pos);
+            int tail = find_tail_number(bottom, head);
+
+            char numstr[8] = {0};
+            make_num_string(bottom, numstr, head, tail);
+
+            prod *= atoi(numstr);
+            adjacent++;
+            botskip = tail;
+            pr_info("%s: Found adjacent number bottom: %d %d-%d v:%d\n", MODULE_NAME, pos, head, tail, atoi(numstr));
+        }
+    }
+
+    if(adjacent == 2) {
+        return prod;
+    } else {
+        return 0;
+    }
+}
+
+
+static int find_stars(char *top, char *middle, char *bottom) {
+    int beginning = -1;
+    int sum = 0;
+
+    for(int i = 0; i < width; i++) {
+        if(middle[i] == '*') {
+            beginning = i;
+            pr_info("%s: Found star: %d\n", MODULE_NAME, i);
+
+            sum += find_adjacent_numbers(top, middle, bottom, beginning);
+        }
+    }
+    return sum;
+}
+
+
+
+static int __init test_init(void) {
+    struct file *f;
+
+    pr_info("%s: Module loaded\n", MODULE_NAME);
+
+    f = filp_open(path, O_RDONLY, 0);
+    if(IS_ERR(f)) {
+        pr_err("%s: Failed to open %s\n", MODULE_NAME, path);
+        return PTR_ERR(f);
+    }
+
+    char buf[3][width+1];
+    memset(buf, 0, sizeof(buf));
+
+    read_input(f, 0, width, buf[2]);
+
+    int sum = 0;
+
+    for(int line = 1; line <= length; line++) {
+        pr_info("%s: %s", MODULE_NAME, buf[2]);
+
+        memcpy(buf[0], buf[1], sizeof(buf[0]));
+        memcpy(buf[1], buf[2], sizeof(buf[1]));
+
+        if(length - line > 0) {
+            read_input(f, line*width, length, buf[2]);
+        } else {
+            memset(buf[2], 0, sizeof(buf[2]));
+        }
+
+        sum += find_stars(buf[0], buf[1], buf[2]);
+    }
+
+    filp_close(f, NULL);
+
+    pr_info("%s: Answer: %d\n", MODULE_NAME, sum);
+    return 0;
+}
+
+static void __exit test_exit(void) {
+    pr_info("%s: Module unloaded\n", MODULE_NAME);
+}
+
+module_init(test_init);
+module_exit(test_exit);

day3/sample2

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+467..114..
+...*......
+..35..633.
+......#...
+617*......
+.....+.58.
+..592.....
+......755.
+...$.*....
+.664.598..