Small fixes: uptime, printf %f, math, and readme

README.md

@@ -19,6 +19,16 @@ The long-term goal of this OS is to be capable of running user programs and havi
 
 ## Usage
 
+Download the latest BlankOS ISO image from the "Releases" tab, and emulate it directly using the QEMU emulator:
+
+```
+qemu-system-i386 blankOS-i386-1.4.45.iso
+```
+
+Alternatively, burn the image on a USB stick and use it on a machine (see section "Real Hardware").
+
+## Building from source
+
 ### Dependencies
 
 For Debian-based distros:
@@ -42,7 +52,7 @@ A cross-compiler is needed to build the system. More info on why [here](https://
 
 Why didn't I use one sooner? Can't tell. Maybe I was too lazy. This is actually problematic because I wasn't able to use some libraries and I had to put in a bunch of weird compilation flags. It's better like this.
 
-## Building and running
+To clone and build, do:
 
 ```
 git clone https://github.com/xamidev/blankos
@@ -50,7 +60,8 @@ make
 make run
 ```
 
-This will start a new Bochs debugger instance. To proceed with the kernel execution, you will have to type `c` in the shell spawning Bochs. Serial output will be saved under the `com1.out` file, this way you can debug the kernel by viewing its log messages. To quit, type `q`. Feel free to open issues or pull requests.
+This will start a new Bochs debugger instance. To proceed with the kernel execution, you will have to type `c` in the shell spawning Bochs. Serial output will be saved under the `com1.out` file, this way you can debug the kernel by viewing its log messages. To quit, type `q`.
+You can try out QEMU too.
 
 ## Running on real hardware
 

src/kernel/kmain.c

@@ -3,6 +3,7 @@
 #include "gdt.h"
 #include "idt.h"
 #include "system.h"
+//#include <stdarg.h>
 
 char* ascii_title =
 "\n"

src/libc/stdio.c

@@ -183,7 +183,6 @@ void dtostrf(double val, char *buffer, int precision)
   double fractional_part = val - whole_part;
   if (fractional_part < 0) fractional_part = -fractional_part;
 
-  char *start = buffer;
   if (whole_part == 0)
   {
     *buffer++ = '0';

src/programs/math.c

@@ -87,7 +87,6 @@ Token lexer_get_next_token(Lexer *lexer)
 				}
 				lexer->current_token.type = TOKEN_NUMBER;
 				lexer->current_token.value = value;
-				//printf("NUMBER %f\n", value);
 				return lexer->current_token;
 		}
 
@@ -95,7 +94,6 @@ Token lexer_get_next_token(Lexer *lexer)
 		{
 			lexer_advance(lexer);
 			lexer->current_token.type = TOKEN_PLUS;
-			printf("PLUS\n");
 			return lexer->current_token;
 		}
 
@@ -103,7 +101,6 @@ Token lexer_get_next_token(Lexer *lexer)
 		{
 			lexer_advance(lexer);
 			lexer->current_token.type = TOKEN_MINUS;
-			printf("MINUS\n");
 			return lexer->current_token;
 		}
 
@@ -111,7 +108,6 @@ Token lexer_get_next_token(Lexer *lexer)
 		{
 			lexer_advance(lexer);
 			lexer->current_token.type = TOKEN_MULTIPLY;
-			printf("MULTIPLY\n");
 			return lexer->current_token;
 		}
 
@@ -119,7 +115,6 @@ Token lexer_get_next_token(Lexer *lexer)
 		{
 			lexer_advance(lexer);
 			lexer->current_token.type = TOKEN_DIVIDE;
-			printf("DIVIDE\n");
 			return lexer->current_token;
 		}
 
@@ -127,7 +122,6 @@ Token lexer_get_next_token(Lexer *lexer)
 		{
 			lexer_advance(lexer);
 			lexer->current_token.type = TOKEN_LPAREN;
-			printf("LPAREN\n");
 			return lexer->current_token;
 		}
 
@@ -135,16 +129,14 @@ Token lexer_get_next_token(Lexer *lexer)
 		{
 			lexer_advance(lexer);
 			lexer->current_token.type = TOKEN_RPAREN;
-			printf("RPAREN\n");
 			return lexer->current_token;
 		}
 
-		printf("Unknown character %c\n", current_char);
-		//shell_install();
+		printf("\nUnknown character %c\n", current_char);
+		shell_install();
 	}
 	
 	lexer->current_token.type = TOKEN_END;
-	printf("END\n");
 	return lexer->current_token;
 }
 
@@ -166,8 +158,8 @@ void parser_eat(Parser *parser, TokenType type)
 	{
 		parser->current_token = lexer_get_next_token(&parser->lexer);
 	} else {
-		printf("Unexpected token %d\n", parser->current_token.type);
-		//shell_install();
+		printf("\nUnexpected token %d\n", parser->current_token.type);
+		shell_install();
 	}
 }
 
@@ -181,17 +173,15 @@ double parser_factor(Parser *parser)
 	if (token.type == TOKEN_NUMBER)
 	{
 		parser_eat(parser, TOKEN_NUMBER);
-		//printf("Factor: %f\n", token.value);
 		return token.value;
 	} else if (token.type == TOKEN_LPAREN) {
 		parser_eat(parser, TOKEN_LPAREN);
 		double result = parser_expression(parser);
 		parser_eat(parser, TOKEN_RPAREN);
-		//printf("Factor (expression): %f\n", result);
 		return result;
 	} else {
-		printf("Unexpected token in factor %d\n", token.type);
-		//shell_install();
+		printf("\nUnexpected token in factor %d\n", token.type);
+		shell_install();
 	}
 	return -1;
 }
@@ -199,7 +189,6 @@ double parser_factor(Parser *parser)
 double parser_term(Parser *parser)
 {
 	double result = parser_factor(parser);
-	//printf("Initial term: %f\n", result);
 
 	while (parser->current_token.type == TOKEN_MULTIPLY || parser->current_token.type == TOKEN_DIVIDE)
 	{
@@ -208,11 +197,9 @@ double parser_term(Parser *parser)
 		{
 			parser_eat(parser, TOKEN_MULTIPLY);
 			result *= parser_factor(parser);
-			//printf("Term after multiply: %f\n", result);
 		} else if (token.type == TOKEN_DIVIDE) {
 			parser_eat(parser, TOKEN_DIVIDE);
 			result /= parser_factor(parser);
-			//printf("Term after divide: %f\n", result);
 		}
 	}
 	return result;
@@ -221,7 +208,6 @@ double parser_term(Parser *parser)
 double parser_expression(Parser *parser)
 {
 	double result = parser_term(parser);
-	//printf("Initial expression: %f\n", result);
 
 	while (parser->current_token.type == TOKEN_PLUS || parser->current_token.type == TOKEN_MINUS) 
 	{
@@ -230,11 +216,9 @@ double parser_expression(Parser *parser)
 		{
 			parser_eat(parser, TOKEN_PLUS);
 			result += parser_term(parser);
-			//printf("Expression after plus: %f\n", result);
 		} else if (token.type == TOKEN_MINUS) {
 			parser_eat(parser, TOKEN_MINUS);
 			result -= parser_term(parser);
-			//printf("Expression after minus: %f\n", result);
 		}
 	}
 	return result;
@@ -245,7 +229,6 @@ double parse(const char* text)
 	Parser parser;
 	parser_init(&parser, text);
 	double result = parser_expression(&parser);
-	//printf("Final result: %f\n", result);
 	return result;
 }
 
@@ -254,7 +237,6 @@ void program_math()
 	char input_buffer[BUFFER_SIZE];
 	puts("Expression? ");
 	get_input(input_buffer, BUFFER_SIZE);
-	printf("Input: %s\n", input_buffer);
 	double result = parse(input_buffer);
 	printf("\n%f\n", result);
 }

src/programs/misc.c

@@ -35,5 +35,7 @@ void program_clear()
 
 void program_uptime()
 {
-	printf("%d ticks\n", uptime());
+	int ticks = uptime();
+	double seconds = ticks/18.2065; // PIC channel 0 freq
+	printf("%d ticks\t%f seconds\n", ticks, seconds);
 }