Finish program and write documentation

README.md

@@ -0,0 +1,40 @@
+# Barcode generator
+
+## About
+This program generates a [Code 39](https://en.wikipedia.org/wiki/Code_39) barcode for a given string. In other words, it draws the appropriate sequences of bars and spaces into a bmp file.
+
+Details of the task can be found in `task.pdf` file.
+
+## How to run
+This project is precompiled for Linux.
+Open terminal in the folder with files.
+
+Type `./program  width_of_narrow_bar text_to_be_encoded`
+
+Where:
+
+`width_of_narrow_bar` - 1, 2 or 3
+
+`text_to_be_encoded`  - sequence of up to 9 characters (uppercase letters, numbers and [more](https://en.wikipedia.org/wiki/Code_39#/media/File:Free_3_of_9_(Code_39_barcode).svg))
+
+A barcode will be generated in the `output.bmp` file.
+
+## Sample run
+```
+./program 2 CODE-X86
+```
+
+In `output.bmp` file:
+
+![example](documentation/example.bmp)
+
+The correctness of the barcode generated can be verified for example with an Android app:
+
+![example](documentation/screenshot-barcode-scanner.png)
+
+## Implementation
+The source for the program is located in `main.c` and `functions.asm` files. It is written in C and 32 bit x86 assembly language. The simplified logic of the core functions in pseudocode is presented in form of diagrams below. 
+The diagrams were created with the MIPS implementation in mind, but are valid in the x86 case as well. 
+
+
+![Logic chart](documentation/logic.drawio.svg) 

functions.asm

@@ -2,6 +2,7 @@ global _put_pixel, put_pixel
 global _put_thin_bar, put_thin_bar
 global _put_thick_bar, put_thick_bar
 global _put_char, put_char
+global _encode39, encode39
 
 section .data
 ;used by put_char
@@ -39,6 +40,9 @@ section	.text
     pop edx
 %endmacro
 
+; used by encode39
+%define STARTING_X 10 ; starting x coordinate of the bar
+
 
 ; int put_pixel(char* pixels, int x, int y);
 ; sets the color of specified pixel to black
@@ -153,7 +157,6 @@ put_thick_bar:
 ; return value: x coordinate of the next character
 _put_char:
 put_char:
-
 	push ebp
 	mov	ebp, esp
 	push ebx
@@ -255,4 +258,69 @@ return:
     pop esi
     pop ebx
 	pop	ebp
-	ret
+	ret
+
+
+; int encode39(char* pixels, int width, char* text);
+; encodes text using Code 39 barcode
+; arguments:
+;	DWORD[ebp+8]:  char* pixels  - address of pixel array
+;   DWORD[ebp+12]: int width  - width in pixels of narrowest bar
+;   DWORD[ebp+16]: char* text  - character to put
+; return value: 0 (OK) or -1 (error, character unsupported)
+_encode39:
+encode39:
+	push ebp
+	mov	ebp, esp
+	push ebx
+
+	mov  edx, STARTING_X
+
+    ; put_char(pixels, x, width, character)
+    push '*'            ; character
+    push DWORD[ebp+12]  ; width
+    push edx     ; x
+    push DWORD[ebp+8]   ; pixels
+    call put_char
+    add  esp, 16
+    mov  edx, eax
+
+    mov ebx, DWORD[ebp+16]
+
+char_loop:
+    mov cl, BYTE[ebx]
+    cmp cl, 0
+    je  ending_char
+
+    ; put_char(pixels, x, width, character)
+    push ecx            ; character
+    push DWORD[ebp+12]  ; width
+    push edx            ; x
+    push DWORD[ebp+8]   ; pixels
+    call put_char
+    add  esp, 12
+    pop  ecx
+    mov  edx, eax
+
+    cmp  eax, -1
+    je   exit
+
+    inc  ebx
+    jmp  char_loop
+
+ending_char:
+    ; put_char(pixels, x, width, character)
+    push '*'            ; character
+    push DWORD[ebp+12]  ; width
+    push edx    ; x
+    push DWORD[ebp+8]   ; pixels
+    call put_char
+    add  esp, 16
+
+set_return_value:
+    xor eax, eax
+
+exit:
+    pop ebx
+    pop	ebp
+    ret

main.c

@@ -1,10 +1,13 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 extern int put_pixel(char* pixels, int x, int y);
 extern int put_thin_bar(char* pixels, int x, int width);
 extern int put_thick_bar(char* pixels, int x, int width);
 extern int put_char(char* pixels, int x, int width, char character);
+extern int encode39(char* pixels, int width, char* text);
+
 
 char* read_from_file();
 char* write_to_file(char* buff);
@@ -13,42 +16,40 @@ unsigned int len;
 
 int main(int argc, char** argv)
 {
+    if(argc !=  3)
+    {
+        printf("Error: Incorrect number of arguments.\n");
+        printf("Correct syntax: ./program width_of_narrow_bar(1, 2 or 3) text_to_be_encoded(max 9 characters).\n ");
+        return 2;
+    }
+
+    int width = atoi(argv[1]);
+    if (width < 1 || width > 3) {
+        printf("Error: Width must be 1, 2 or 3.\n");
+        return 3;
+    }
+
+    char* text = argv[2];
+    if (strlen(text) > 9) {
+        printf("Error: Length of text to encode must be between 1 and 9 characters.\n");
+        return 4;
+    }
+
+    printf("width: %d, text: %s\n", width, text);
+
     char* buff = read_from_file();
     char* pixels = buff + 10;
     pixels = buff + pixels[0];
     // pixels pointer now points to the pixels section of .bmp
-//    if(ret == -1) {
-//        printf("Error 1: Text contains characters which cannot be encoded");
-//        return 1;
-//    }
-//    printf("return value: %d ", ret);
-
-    int ret = 10;
-    ret = put_char(pixels, ret, 2, '*');
-    ret = put_char(pixels, ret, 2, 'B');
-    ret = put_char(pixels, ret, 2, 'A');
-    ret = put_char(pixels, ret, 2, 'C');
-    ret = put_char(pixels, ret, 2, 'A');
-    put_char(pixels, ret, 2, '*');
-
-
-//    put_pixel(pixels, 20, 20);
-//    int ret = put_thick_bar(pixels, 20, 2);
 
-//    put_thin_bar(pixels, ret, 2);
+    int ret = encode39(pixels, width, text);
+    if(ret == -1) {
+        printf("Error: Text contains characters which cannot be encoded");
+        return 1;
+    }
 
     write_to_file(buff);
 
-
-//    if(argc !=  2)
-//    {
-//        printf("Input argument was not specified correctly! \n ");
-//        return -1;
-//    }
-
-//    if (result == 0) printf("No shape found.\n");
-//    else printf("Shape %i found.\n\n\n", result);
-
     return 0;
 }
 
@@ -58,10 +59,10 @@ char* read_from_file() {
     imgFile = fopen("white.bmp", "rb");
     if (imgFile == NULL)
     {
-        printf("Failed to open file\n");
+        printf("Failed to open white.bmp\n");
         exit(-1);
     }
-    else printf("File opened successfully\n");
+    else printf("white.bmp opened successfully\n");
 
     fseek(imgFile, 0, SEEK_END); /* move file pointer to end of file */
     len = ftell(imgFile); /* get offset from beginning of the file */
@@ -95,11 +96,6 @@ char* write_to_file(char* buff) {
     }
     else printf("File to write to opened successfully\n");
 
-//    int width =*(int * )( & buff[18] ); // width = 600
-//    int width = 600;
-//    int height =*(int * )( & buff[22] ); // height = 50
-//    int height = 50;
-    int size = ((600 * 3 + 3) & ~3) * 50 + 54;
     fwrite(buff, len, 1, imgFile);
     fclose(imgFile);