82 lines
2.7 KiB
ArmAsm
82 lines
2.7 KiB
ArmAsm
;;; -*- Mode: asm; indent-tabs-mode: t; tab-width: 8 -*-
|
|
;; petski: https://www.c64-wiki.com/wiki/File:ASCII-Codes.gif
|
|
;;https://www.c64-wiki.com/wiki/Character_set
|
|
;; Takes in a PETSKI-code in CODE
|
|
;; And prints it ON X_pos, Y_pos
|
|
;; Note that this is the real positions divided by 8
|
|
.proc char_draw
|
|
Y_pos_offset = $F9F8 ;Reuses from Y_pos
|
|
X_pos_offset = $FAF7
|
|
X_pos = $FA
|
|
Y_pos = $F9
|
|
charset = $FB
|
|
code = $FE
|
|
petski_position = $FEFF ;reuses code:s memory
|
|
screen_position = $FCFD
|
|
|
|
;#### TEMP INIT DATA ####
|
|
LDA #$10
|
|
STA code
|
|
LDA #04
|
|
STA X_pos
|
|
LDA #02
|
|
STA Y_pos
|
|
|
|
;;Do arithimatic to know where to read and write bytes.
|
|
initial:
|
|
;We first need to clear some memory
|
|
LDA #$00
|
|
STA <petski_position
|
|
STA <Y_pos_offset
|
|
STA <X_pos_offset
|
|
|
|
;;We need the relative offset for bytes to read and write.
|
|
;; This is code *8 because 8byte is one character
|
|
;; *8 = 2*2*2
|
|
ASL code ;Will never owerflow, therefore 8byte
|
|
Mult_16 >petski_position, <petski_position
|
|
Mult_16 >petski_position, <petski_position
|
|
;; Add starting position
|
|
Add_16 >petski_position, <petski_position, #<Character_generator_ROM , #>Character_generator_ROM, !
|
|
|
|
;;Calculate screen_position to use
|
|
Mov_16 >screen_position, <screen_position, #<VIC_bank, #>VIC_bank
|
|
|
|
;; Add the X_pos has a offset multiplier of *8 because 1 chunk = 8 addresses
|
|
;; *8
|
|
Mult_16 >X_pos_offset, <X_pos_offset
|
|
Mult_16 >X_pos_offset, <X_pos_offset
|
|
Mult_16 >X_pos_offset, <X_pos_offset
|
|
;; Add
|
|
Add_16 >screen_position, <screen_position, X_pos, #$00, !
|
|
|
|
;; And Y_pos has a offset multiplier of "screen length" = 320 = (2*2 +1)*2^6
|
|
;;Y_pos*2*2 +1 |Lets reuse X_pos for storage
|
|
LDA Y_pos
|
|
STA X_pos
|
|
Mult_16 >Y_pos_offset, <Y_pos_offset
|
|
Mult_16 >Y_pos_offset, <Y_pos_offset
|
|
Add_16 >Y_pos_offset, <Y_pos_offset, X_pos, #$00, !
|
|
;; *2^6
|
|
Mult_16 >Y_pos_offset, <Y_pos_offset
|
|
Mult_16 >Y_pos_offset, <Y_pos_offset
|
|
Mult_16 >Y_pos_offset, <Y_pos_offset
|
|
Mult_16 >Y_pos_offset, <Y_pos_offset
|
|
Mult_16 >Y_pos_offset, <Y_pos_offset
|
|
Mult_16 >Y_pos_offset, <Y_pos_offset
|
|
;; Add
|
|
Add_16 >screen_position, <screen_position, >Y_pos_offset, <Y_pos_offset, !
|
|
initial_end:
|
|
|
|
|
|
;; One character is 8 byte, move these bytes to screen
|
|
LDY #$07
|
|
@loop:
|
|
LDA (>petski_position), Y
|
|
STA (>screen_position), Y
|
|
DEY
|
|
BNE @loop
|
|
LDA (>petski_position), Y
|
|
STA (>screen_position), Y
|
|
RTS
|
|
.endproc
|