Entry Thread - Karate Kick

Karate Kick
By Michael Moffitt
------------------

This is a port of a little game I made for iOS about five years ago under the
same name. It is a very simple arcade-style game that gets progressively more
difficult as time passes. The player controls a karate master (who only kicks?)
in the center of a dojo, defending against many identical goons who seek a
challenge.

Fortunately, your karate master is so skilled that if he is even looking at an
opponent, the opponent is sure to fall. All you must do is use the d-pad to
turn the karate master towards an incoming enemy. If he's facing the enemy,
he will be victorious. Do not allow an enemy to strike the master's sides or
back.

This entry was thrown together rather hastily, developed mostly on two long
plane flights, as the original entry grew too large and would have no place
on the mluti-card.

The code is available at https://github.com/mikejmoffitt/kkick

@waitvbl1:
   lda #$80
   bit PPUSTATUS
   bne @waitvbl1

@waitvbl1:
   bit PPUSTATUS
   bpl @waitvbl1

@clrmem:
   sta $000, x
   sta $100, x
   ; Reserving $200 for OAM display list
   sta $300, x
   sta $400, x
   sta $500, x
   sta $600, x

.macro ppu_load_scroll cam_x, cam_y
   bit PPUSTATUS
   lda cam_x
   sta PPUSCROLL
   lda cam_y
   sta PPUSCROLL
   ; Clamp scroll values
   lda xscroll+1
   and #%00000001
   sta xscroll+1
   lda yscroll+1
   and #%00000001
   sta yscroll+1

   lda ppuctrl_config
   ora xscroll+1         ; Bring in X scroll coarse bit
   ora yscroll+1         ; Y scroll coarse bit
   sta PPUCTRL           ; Re-enable NMI
.endmacro

   txa            ; X still = 0; clear A with this
   lda $55
@clrmem:
   sta $000, x
   sta $100, x
...

; This patch NOPs out a stray load from zero page in RAM clearing
patch=B162=EAEA

LDA $5555