Add 2015 - Day 1 - Part 1

.idea/runConfigurations/AOC_2015_1.xml

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+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="AOC_2015_1" type="CMakeRunConfiguration" factoryName="Application" REDIRECT_INPUT="false" ELEVATE="false" USE_EXTERNAL_CONSOLE="false" WORKING_DIR="file://$PROJECT_DIR$/2015/01" PASS_PARENT_ENVS_2="true" PROJECT_NAME="AOC" TARGET_NAME="AOC_2015_1" CONFIG_NAME="Debug" RUN_TARGET_PROJECT_NAME="AOC" RUN_TARGET_NAME="AOC_2015_1">
+    <method v="2">
+      <option name="com.jetbrains.cidr.execution.CidrBuildBeforeRunTaskProvider$BuildBeforeRunTask" enabled="true" />
+    </method>
+  </configuration>
+</component>

2015/01/CMakeLists.txt

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+set(PROJECT_NAME AOC_2015_1)
+
+project(${PROJECT_NAME} C ASM_NASM)
+enable_language(ASM_NASM)
+
+set(CMAKE_NASM_LINK_EXECUTABLE "ld <LINK_FLAGS> <OBJECTS> -o <TARGET> <LINK_LIBRARIES>")
+set(CAN_USE_ASSEMBLER TRUE)
+
+add_executable(${PROJECT_NAME} main.asm main.c)

2015/01/main.asm

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+bits 32
+
+section .data
+section .text
+
+global _walkFloors
+
+_walkFloors:
+  enter 0,0
+  push ebx
+
+  mov eax, [ ebp +  8 ] ; eax = currentFloor
+  mov edx, [ ebp + 12 ] ; edx = char* instructions
+  mov ecx, [ ebp + 16 ] ; ecx = size_t instructionCount
+
+  jcxz .end ; skip to end if there are no instructions
+
+  inc ecx ; increment instruction count by 1
+          ; because loop instruction uses prefix decrement
+
+.instructionLoop:
+  mov bl, [ edx ] ; bl = instructions[edx]
+  inc edx         ; edx++
+
+  cmp bl, '('     ; left parenthesis...
+  je .moveUpFloor ; moves up a floor
+
+  cmp bl, ')'       ; right parenthesis...
+  je .moveDownFloor ; moves down a floor
+
+  jmp .end ; unknown character skips to the end
+
+.moveUpFloor:
+  inc eax
+  loop .instructionLoop
+
+.moveDownFloor:
+  dec eax
+  loop .instructionLoop
+
+.end:
+  pop ebx
+  leave
+  ret

2015/01/main.c

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+#include "stdio.h"
+
+#define BUFFER_SIZE 256
+
+int walkFloors(int currentFloor, char* instructions, size_t instructionCount);
+
+int main() {
+	FILE* file;
+	errno_t openErr = fopen_s(&file, "input/1.txt", "rb");
+	if (openErr != 0 || !file) {
+		printf("Error opening input file, code %d\n", openErr);
+		return 1;
+	}
+	
+	int floor = 0;
+	
+	char buffer[BUFFER_SIZE];
+	while (!feof(file)) {
+		size_t readBytes = fread_s(&buffer, BUFFER_SIZE, 1, BUFFER_SIZE, file);
+		
+		int readErr = ferror(file);
+		if (readErr) {
+			printf("Error reading input file, code %d\n", readErr);
+			return 1;
+		}
+		
+		floor = walkFloors(floor, buffer, readBytes);
+	}
+	
+	fclose(file);
+	printf("Final floor: %d", floor);
+	return 0;
+}

CMakeLists.txt

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+cmake_minimum_required(VERSION 3.20)
+
+project(AOC)
+
+add_subdirectory(2015/01)