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;; Clear the carry and add ADDR to the indexed digit on 'Score::m_players'. If
;; the result is larger or equal than 10, then 0 is stored and the carry flag is
;; set. Otherwise the carry flag is cleared.
.macro BCD_ADD ADDR
lda Score::m_players, x
clc
adc ADDR
cmp #10
bcc :+
sec
lda #0
:
sta Score::m_players, x
.endmacro
;; Add ADDR to the indexed digit on 'Score::m_players' _with_ carry. If the
;; result is larger or equal than 10, then 0 is stored and the carry flag is
;; set. Otherwise the carry flag is cleared.
.macro BCD_ADDC ADDR
lda Score::m_players, x
adc ADDR
clc
cmp #10
bcc :+
sec
lda #0
:
sta Score::m_players, x
.endmacro
;; Only add the carry to the indexed digit on 'Score::m_players' _with_
;; carry. If the result is larger or equal than 10, then 0 is stored and the
;; carry flag is set. Otherwise the carry flag is cleared.
.macro BCD_JUST_CARRY
lda Score::m_players, x
adc #0
clc
cmp #10
bne :+
sec
lda #0
:
sta Score::m_players, x
.endmacro
;; A score is a 6-digit number where each digit is stored on a byte of its
;; own. This makes adding numbers and representing them into the screen dead
;; easy.
;;
;; This is indeed rather wasteful, but we have a lot of RAM to spare and the
;; ease of use is quite convenient.
.scope Score
;; Scores for both players are stored in a single buffer. Even indeces
;; contain digits for the first player, and odd indeces contain digits for
;; the second player. Digits are stored in little-endian format.
;;
;; Interweaving digits this way might seem weird, but it actually makes
;; indexing things super easy: the 'active' bit from
;; 'Globals::zp_multiplayer' can be used to index the first item, and then
;; it's a matter of advancing the 'x' register twice in order to get the
;; next digit.
PLAYERS_BUFF_SIZE = $0C
m_players = $300 ; asan:reserve PLAYERS_BUFF_SIZE
;; The high score for this session.
m_hi = $30C ; asan:reserve $06
;; Initialize the scores for both players.
.proc init_players_scores
lda #0
ldx #0
@loop:
sta m_players, x
inx
cpx #PLAYERS_BUFF_SIZE
bne @loop
rts
.endproc
;; Add to the current player's score the number stored in
;; 'Globals::zp_tmp{0,1,2}', where 'Globals::zp_tmp0' has the least
;; significant number.
.proc add_to_player
;; See 'Score::m_players' on why this is the way to select the current
;; player's score.
lda Globals::zp_multiplayer
and #$01
tax
;;;
;; The first three digits are the product of adding the contents of
;; 'Globals::zp_tmp{0,1,2}'.
BCD_ADD Globals::zp_tmp0
inx
inx
BCD_ADDC Globals::zp_tmp1
inx
inx
BCD_ADDC Globals::zp_tmp2
inx
inx
;;;
;; The rest are just a matter of adding the carry.
BCD_JUST_CARRY
inx
inx
BCD_JUST_CARRY
inx
inx
BCD_JUST_CARRY
;; TODO: set a flag about updating the score on the HUD.
rts
.endproc
.endscope
;; Add the score for a dead enemy to the current player's score.
.macro ADD_ENEMY_SCORE
lda #5
sta Globals::zp_tmp0
lda #2
sta Globals::zp_tmp1
lda #0
sta Globals::zp_tmp2
jsr Score::add_to_player
.endmacro
;; Add the score for grabbing a shuttle part / fuel tank to the current player's
;; score.
.macro ADD_PART_FUEL_SCORE
lda #0
sta Globals::zp_tmp0
lda #0
sta Globals::zp_tmp1
lda #1
sta Globals::zp_tmp2
jsr Score::add_to_player
.endmacro
;; Add the score for grabbing an item to the current player's score.
.macro ADD_ITEM_SCORE
lda #0
sta Globals::zp_tmp0
lda #5
sta Globals::zp_tmp1
lda #2
sta Globals::zp_tmp2
jsr Score::add_to_player
.endmacro
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