From f66cbfcd6430b30a83e35c404ff3979aa3a55a30 Mon Sep 17 00:00:00 2001
From: bylex <mbilek06@gmail.com>
Date: Thu, 3 Oct 2024 16:10:23 +0200
Subject: [PATCH] Improve assembler

fix errors and add label support
---
 assembler.c | 119 +++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 109 insertions(+), 10 deletions(-)

diff --git a/assembler.c b/assembler.c
index 09bc341..54394fc 100644
--- a/assembler.c
+++ b/assembler.c
@@ -1,3 +1,4 @@
+#include <ctype.h>
 #include <stdio.h>
 #include <string.h>
 #include <stdbool.h>
@@ -15,19 +16,50 @@ struct inst_t
 	uint8_t params[3];
 } instruction_default = {false, 0, 0, 0, 0};
 
-void parse_line(FILE** input_file)
+struct label_t
 {
-	char line_buffer[256];	
+	char* label_name;
+	uint16_t addr;
+};
+
+struct inst_t parse_line(char* line_buffer, struct label_t* labels, unsigned int* labels_len)
+{
+	static unsigned int labels_index = 0;
+	static uint16_t current_addr = 0;
 
 	int token_count = 0;
 	char* token;
 	struct inst_t inst = instruction_default;
 
-	fgets(line_buffer, 256, *input_file);
-
 	if(line_buffer[0] == ';')
 	{
-		return;
+		return inst;
+	}
+	else if(line_buffer[0] == '$')
+	{
+		struct label_t label;
+
+		int i = 0;
+		while(i <  256)
+		{
+			if(isspace(line_buffer[i]))
+			{
+				line_buffer[i] = '\0';
+			}
+			i++;
+		}
+
+		label.label_name = malloc(256);
+		strcpy(label.label_name, line_buffer);
+		label.addr = current_addr;
+		if(labels_index + 1 == labels_len)
+		{
+			*labels_len = *labels_len + 16;
+			labels = realloc(labels, (*labels_len) * sizeof(struct label_t));
+		}
+		labels[labels_index] = label;
+		labels_index++;
+		return inst;
 	}
 	else
 	{
@@ -44,6 +76,19 @@ void parse_line(FILE** input_file)
 				uint8_t i = 0;
 				while(i < N_INSTRUCTIONS - 1)
 				{
+					int token_len = strlen(token);
+					if(token_len != 3)
+					{
+						int i = 0;
+						while(i < token_len)
+						{
+							if(isspace(token[i]))
+							{
+								token[i] = '\0';
+							}
+							i++;
+						}
+					}
 					if(strcmp(token, opcodes_strings[i]) == 0)
 					{
 						inst.instruction_code = i;
@@ -58,8 +103,46 @@ void parse_line(FILE** input_file)
 				break;
 			case 2: 
 				// current token is second parameter
-				uint16_t token_int = atoi(token);
-				inst.params[1] = token_int;
+				if(token[0] == '$')
+				{
+					int i = 0;
+					int token_len = strlen(token);
+					while(i < token_len)
+					{
+						if(isspace(token[i]))
+						{
+							token[i] = '\0';
+						}
+						i++;
+					}
+
+					int j = 0;
+					bool label_known = false;
+					while(j < labels_index)
+					{
+						if(strcmp(labels[j].label_name, token) == 0)
+						{
+							inst.params[1] = (uint8_t)(labels[j].addr >> 8);
+							inst.params[2] = (uint8_t)(labels[j].addr);
+							label_known = true;
+							break;
+						}
+						j++;
+					}
+					if(!label_known)
+					{
+						perror("Unknown identifier\n");
+						exit(1);
+					}
+					break;
+				}
+				else
+				{
+					uint16_t token_int = atoi(token);
+					inst.params[1] = (uint8_t)(token_int >> 8);
+					inst.params[2] = (uint8_t)(token_int);
+					break;
+				}
 				break;
 			case 3: 
 				// current token is third parameter
@@ -68,10 +151,22 @@ void parse_line(FILE** input_file)
 		token_count++;
 		token = strtok(NULL, " ");
 	}
+	current_addr = current_addr + 4;
+	return inst;
+}
+
+void write_instruction(FILE** output_file, struct inst_t inst)
+{
+	if(inst.contains_instruction)
+	{
+		fwrite(&inst.instruction_code, sizeof(uint8_t), 4, *output_file);
+	}
 }
 
 int main(int argc, char *argv[])
 {
+	unsigned int labels_len = 10;
+	struct label_t* labels = malloc(labels_len * sizeof(struct label_t));
 
 	if(argc <= 2 || argc >= 4)
 	{
@@ -86,14 +181,18 @@ int main(int argc, char *argv[])
 		return 1;
 	}
 
-	FILE* output_file = fopen(argv[2], "w");
+	FILE* output_file = fopen(argv[2], "wb");
 	if(!output_file)
 	{
 		perror("Cannot open output file for writing\n");
 		return 1;
 	}
-	while(!feof(input_file))
+
+	unsigned int line_num = 0;
+	char line_buffer[256];	
+	while(fgets(line_buffer, 256, input_file))
 	{
-		parse_line(&input_file);
+		line_num++;
+		write_instruction(&output_file, parse_line(line_buffer, labels, &labels_len));
 	}
 }
-- 
2.25.1