From c2efe3c9f0d42279233d634dfe06dff66d36d422 Mon Sep 17 00:00:00 2001
From: "Alexander \"Arav\" Andreev" <me@arav.su>
Date: Sun, 3 Dec 2023 18:36:14 +0400
Subject: [PATCH] Let's replace a func call with a simple macro that just
 checks for if a character is between 0x30 ('0') to 0x39 ('9').

---
 day3/p2.c | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/day3/p2.c b/day3/p2.c
index 753be5c..be9cf63 100644
--- a/day3/p2.c
+++ b/day3/p2.c
@@ -6,6 +6,8 @@
 #include <stdbool.h>
 #include <ctype.h>
 
+#define ISDIGIT(c) (c >= 0x30 && c <= 0x39)
+
 int32_t parse_number(char *line, ssize_t j);
 
 int main(int argc, char **argv) {
@@ -48,38 +50,38 @@ int main(int argc, char **argv) {
             int32_t n = 1;
             int8_t p = 0;
 
-            if (isdigit(engine[i][j+1])) {
+            if (ISDIGIT(engine[i][j+1])) {
                 n *= parse_number(engine[i], j+1);
                 p++;
             }
-            if (isdigit(engine[i][j-1])) {
+            if (ISDIGIT(engine[i][j-1])) {
                 n *= parse_number(engine[i], j-1);
                 p++;
             }
 
-            if (isdigit(engine[i+1][j])) {
+            if (ISDIGIT(engine[i+1][j])) {
                 n *= parse_number(engine[i+1], j);
                 p++;
             } else {
-                if (isdigit(engine[i+1][j+1])) {
+                if (ISDIGIT(engine[i+1][j+1])) {
                     n *= parse_number(engine[i+1], j+1);
                     p++;
                 }
-                if (isdigit(engine[i+1][j-1])) {
+                if (ISDIGIT(engine[i+1][j-1])) {
                     n *= parse_number(engine[i+1], j-1);
                     p++;
                 }
             }
 
-            if (isdigit(engine[i-1][j])) {
+            if (ISDIGIT(engine[i-1][j])) {
                 n *= parse_number(engine[i-1], j);
                 p++;
             } else {
-                if (isdigit(engine[i-1][j+1])) {
+                if (ISDIGIT(engine[i-1][j+1])) {
                     n *= parse_number(engine[i-1], j+1);
                     p++;
                 }
-                if (isdigit(engine[i-1][j-1])) {
+                if (ISDIGIT(engine[i-1][j-1])) {
                     n *= parse_number(engine[i-1], j-1);
                     p++;
                 }
@@ -103,9 +105,9 @@ int32_t parse_number(char *line, ssize_t j) {
     int32_t n = 0;
     int32_t multiplier = 1;
 
-    while (isdigit(line[j+1])) j++;
+    while (ISDIGIT(line[j+1])) j++;
 
-    while (isdigit(line[j])) {
+    while (ISDIGIT(line[j])) {
         n += (line[j]&0xf) * multiplier;
         multiplier *= 10;
         j--;