.arch parva_0_1

# 1(sp): score
# 2(sp): swap_block

# x4: block lines 0/1
# x5: block lines 2/3
# x6: field lines 0/1
# x7: field lines 2/3

.include consts
.include sys

.string_encoding sys-6


.data.ro

srs_kick_table:
# XY, 0 = 0, 1 = +1, 2 = +2, 7 = -1, 6 = -2
# I block
0o60_10_67_12
0o70_20_72_27
# TODO
# J, L, T, S, Z blocks
0o70_71_06_76
0o10_17_02_12
# TODO

block_table:
# I 0
0b_0_0000_000000_0_0_1111_000000_0
0b_0_1111_000000_0_0_0000_000000_0
# I 1
0b_0_0010_000000_0_0_0010_000000_0
0b_0_0010_000000_0_0_0010_000000_0
# TODO

hi_score_filename: .string "tet_hiscr.dat\0"
hi_score_file_error_message: .string .line_break 10 "could not open or create hi score file\0"
score_string: .string "score\0"
game_over_string: .string "game over\0"
.scores_button_string: .string "scores\0"
.start_button_string: .string "start\0"
.next_string: .string "next\0"

.data.rw

.align const.cache_line_size
swap_block: 0
score: 0
next_air_drop_time: 0
next_floor_drop_time: 0
stack: .repeat 0, 20

hi_scores:
.repeat 0, 20

.eq score_string_x 30
.eq score_string_y 10


.text 

_start:

push ra

load_hi_scores:

li a0, hi_score_filename
li a1, hi_scores
li x0, 20
call sys.read_file
li x0, -1
beq a0, x0, create_hi_score_file

create_hi_score_file:

li a0, hi_score_filename
call sys.open_file

bltz a0, error_hi_score_file

wait:

wait_loop:

stub.kb.rdchar x0

beqi x0, const.char.left_arrow, move_left
beqi x0, const.char.right_arrow, move_right
beqi x0, const.char.up_arrow, rotate
beqi x0, const.char.space, hard_drop
beqi x0, const.char.backspace, swap

b wait_loop

rotate:

# x2 = current pos / block / rotation, [0 * 8, 4 bits for position x, 0 * 7, 3 bits for block type, 2 bits for rotation]

addi x3, x2, 1
andi x3, x3, 0b00011
andi x2, x2, 0b11100
or x2, x2, x3
ld d0, [x2 + block_table]


.align 4
move_left:

slli x0, x4, 1
and x0, x0, x6
bnez x0, fail
slli x0, x5, 1
and x0, x0, x7
bnez x0, fail

slli x4, x4, 1
slli x5, x5, 1
b move_successful

.align 4
move_right:

srli x0, x4, 1
and x0, x0, x6
bnez x0, fail
srli x0, x5, 1
and x0, x0, x7
bnez x0, fail

srli x4, x4, 1
srli x5, x5, 1
b move_successful

move_failed:

# TODO

move_successful:

# TODO

# decimal addition
# input: x0 = score change
.align 2
add_score:

lw x1, score
add x0, x0, x1
li x1, 0o1166
and x2, x0, 0o77
li x3, 10
blt x2, x3, 2

add x0, x0, x1
slli x1, x1, 6
srli x2, x0, 6
andi x2, x0, 0o77
blt x2, x3, end_score_change
add x0, x0, x1

slli x1, x1, 6
srli x2, x0, 6
andi x2, x0, 0o77
blt x2, x3, end_score_change
add x0, x0, x1
slli x1, x1, 6

srli x2 x0, 6
andi x2, x0, 0o77
blt x2, x3, end_score_change
add x0, x0, x1

.align 2
end_score_change:

sw x0, score




quit:



pop ra