add documentation

wip-duuqnd/loader.s

@@ -1,37 +1,61 @@
 ;;; -*- Mode: asm; indent-tabs-mode: t; tab-width: 8 -*-
 
+;;This program reads a data stream from the joystick port and saves it in memory.
+;;The datastream format is as sutch:
+;;
+;;############################################
+;; 16-bit byte-length (big endian) | data
+;;############################################
+
+;; The data comes from CTRL2 bit 0 and the clock is at bit 1
+
+;; The stream starts when the clock is pulled high, after that comes a
+;; 16-bit big endian number that matches the byte-lenght of the data that will get sent.
+;; When the hole stream has ended the clock is pulled low until the next stream!
+
+;; The data is then stored in ram with the first byte in progdest and the last in progdest + byte-length
+
+;; At the end the program run the code stored at progdest with a jmp!
+
+
+;; More documentation on the Joystick port can be found here: https://www.c64-wiki.com/wiki/Joystick
+
+
 	CLKMASK	=	%00000010
 	CTRL2	=	$DC00
 
 	.org $80d
-coldstart:
+coldstart: ;; Draw a dollar sign on screen to show that program has loaded
 	lda #$0
 	sta $400
-waitstart:
+waitstart: ;; Wait until joystick 1 has been pulled forwards to start this program
 	lda $dc01
 	and #$01
 	bne waitstart
+
+	;; Change boarder colour for debuging
 	lda #$00
 	sta $d020
 teststart:
-	jsr check_for_load_start
+	jsr check_for_load_start ; Check if start_bit is correct
-	bcs @error
+	bcs @error   ; Idk why C=1 ask john
 	beq teststart
-	jmp $c000
+	jmp $c000   ; starts the program?
 	jmp $c000
 @error:
 	lda #1
-	sta $0400
+	sta $0400 ;lets store 1 att this address for debuging purposes
 	rts
 
 check_for_load_start:
 	lda #CLKMASK
 	bit CTRL2
-	bne start
+	bne start ; branch if Z ==0 <--> CTRL2 and CLKMASK ==0 <---> CTRL2 bit 2 == 0
 	lda #$00
 	rts
 start:
 	sei
+	;; change boarder collor for debuging purposes
 	ldx #$02
 	stx $d020
 	ldy #$00
@@ -85,6 +109,8 @@ wait_for_bit_start:
 	jmp done
 @notdone:
 new_byte:
+;; BYTE is the byte beaing read from the stream. The bits are shifted from the left
+;; When we shift out this 1 in BYTE bellow we save the BYTE to memory.
 	lda #%10000000
 	sta BYTE
 wait_for_bit_end: