Add in-program help

README.md

@@ -18,7 +18,6 @@ Missing features
 
 - Ability to set the seed manually
 - Hard and extra hard modes
-- In-program help
 
 Word lists
 ----------

dosdl.asm

@@ -3,8 +3,26 @@ cpu 8086
 
 org 0x100
 
+args_length equ 0x80
+args_area equ 0x81
+
 section .code
 
+parse_arguments:
+	; TODO: Implement argument parsing
+	xor ch, ch
+	mov cl, [args_length]
+
+	test cx, cx
+	jz seed_rng_date
+
+print_help:
+	mov ah, 9
+	mov dx, help_str
+	int 0x21
+
+	ret
+
 seed_rng_date:
 	; Get date
 	mov ah, 0x2a
@@ -68,6 +86,11 @@ load_target:
 	cmp byte [target], '{'
 	je select_target
 
+print_greeting:
+	mov ah, 9
+	mov dx, greeting_str
+	int 0x21
+
 read_guess:
 	; Number of thus far guessed letters stored in bx
 	xor bx, bx
@@ -775,6 +798,8 @@ day db 0
 
 section .rodata
 
+greeting_str db 'Welcome to hello DOSdl. Run `dosdl /?` for help.', 13, 10, '$'
+
 space_dash_space_str db ' - $'
 not_found_str db 'word not found$'
 erase_word_str db '     $'
@@ -783,5 +808,19 @@ correct_in_str db 'Correct in $'
 guesses_str db ' guesses.$'
 guess_str db ' guess.$'
 
+help_str:
+	db 'Usage: dosdl', 13, 10
+	db 13, 10
+	db 'Hello DOSdl is a word guessing game. You have six tries to guess the correct', 13, 10
+	db 'English word. After a guess the game displays feedback under each letter:', 13, 10
+	db 13, 10
+	db "' ' Letter is in the correct place.", 13, 10
+	db "'^' Letter is in the wrong place.", 13, 10
+	db "'x' Letter is not in used in the word, or its uses are already covered by the", 13, 10
+	db '    above cases.', 13, 10
+	db 13, 10
+	db 'After the feedback, the game shows a list of letters that have not yet been', 13, 10
+	db 'ruled out.$'
+
 %include "dictionary.inc"
 %include "targets.inc"