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SixtyPical/eg/proto-game.60p

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// ****************************
// * Demo Game for SixtyPical *
// ****************************
// ----------------------------------------------------------------
// System Locations
// ----------------------------------------------------------------
byte vic_border @ 53280
byte vic_bg @ 53281
byte table[256] screen1 @ 1024
byte table[256] screen2 @ 1274
byte table[256] screen3 @ 1524
byte table[256] screen4 @ 1774
byte table[256] colormap1 @ 55296
byte table[256] colormap2 @ 55546
byte table[256] colormap3 @ 55796
byte table[256] colormap4 @ 56046
buffer[2048] screen @ 1024
byte joy2 @ $dc00
// ----------------------------------------------------------------
// Global Variables
// ----------------------------------------------------------------
pointer ptr @ 254
word table[256] actor_pos
word pos
word new_pos
word table[256] actor_delta
word delta
byte button_down : 0 // effectively static-local to check_button
byte table[18] press_fire_msg: "PRESS`FIRE`TO`PLAY"
byte save_x
word compare_target
//
// Points to the routine that implements the current game state.
//
// It's very arguable that screen1/2/3/4 and colormap1/2/3/4 are not REALLY inputs.
// They're only there to support the fact that game states sometimes clear the
// screen, and sometimes don't. When they don't, they preserve the screen, and
// currently the way to say "we preserve the screen" is to have it as both input
// and output. There is probably a better way to do this, but it needs thought.
//
vector dispatch_game_state
inputs joy2, button_down, press_fire_msg, dispatch_game_state, save_x,
actor_pos, pos, new_pos, actor_delta, delta,
screen, screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
outputs button_down, dispatch_game_state,
actor_pos, pos, new_pos, actor_delta, delta,
screen, screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
trashes a, x, y, c, z, n, v, ptr, save_x, compare_target
//
// The constraints on these 2 vectors are kind-of sort-of big fibs.
// They're only written this way so they can be compatible with our
// routine. In fact, CINV is an interrupt routine where it doesn't
// really matter what you trash anyway, because all registers were
/// saved by the caller (the KERNAL) and will be restored by the end
// of the code of the saved origin cinv routine that we goto.
//
// I wonder if this could be arranged somehow to be less fibby, in
// a future version of SixtyPical.
//
vector cinv
inputs joy2, button_down, press_fire_msg, dispatch_game_state, save_x,
actor_pos, pos, new_pos, actor_delta, delta,
screen, screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
outputs button_down, dispatch_game_state,
actor_pos, pos, new_pos, actor_delta, delta,
screen, screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
trashes a, x, y, c, z, n, v, ptr, save_x, compare_target
@ 788
vector save_cinv
inputs joy2, button_down, press_fire_msg, dispatch_game_state, save_x,
actor_pos, pos, new_pos, actor_delta, delta,
screen, screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
outputs button_down, dispatch_game_state,
actor_pos, pos, new_pos, actor_delta, delta,
screen, screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
trashes a, x, y, c, z, n, v, ptr, save_x, compare_target
// ----------------------------------------------------------------
// Utility Routines
// ----------------------------------------------------------------
routine read_stick
inputs joy2
outputs delta
trashes a, x, z, n
{
ld x, joy2
ld a, x
and a, 1 // up
if z {
copy $ffd8, delta // -40
} else {
ld a, x
and a, 2 // down
if z {
copy word 40, delta
} else {
ld a, x
and a, 4 // left
if z {
copy $ffff, delta // -1
} else {
ld a, x
and a, 8 // right
if z {
copy word 1, delta
} else {
copy word 0, delta
}
}
}
}
}
// You can repeatedly (i.e. as part of actor logic or an IRQ handler)
// call this routine.
// Upon return, if carry is set, the button was pressed then released.
routine check_button
inputs joy2, button_down
outputs c, button_down
trashes a, z, n
{
ld a, button_down
if z {
ld a, joy2
and a, $10
if z {
ld a, 1
st a, button_down
}
st off, c
} else {
ld a, joy2
and a, $10
if not z {
ld a, 0
st a, button_down
st on, c
} else {
st off, c
}
}
}
routine clear_screen
outputs screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
trashes a, y, c, n, z
{
ld y, 0
repeat {
ld a, 1
st a, colormap1 + y
st a, colormap2 + y
st a, colormap3 + y
st a, colormap4 + y
ld a, 32
st a, screen1 + y
st a, screen2 + y
st a, screen3 + y
st a, screen4 + y
inc y
cmp y, 250
} until z
}
routine calculate_new_position
inputs pos, delta
outputs new_pos
trashes a, c, n, z, v
{
copy pos, new_pos
st off, c
add new_pos, delta
}
routine check_new_position_in_bounds
inputs new_pos
outputs c
trashes compare_target, a, z, n, v
{
copy 1000, compare_target
st on, c
sub compare_target, new_pos
if not c {
copy word 0, compare_target
st on, c
sub compare_target, new_pos
if not c {
st off, c
} else {
st on, c
}
} else {
st on, c
}
}
routine init_game
inputs actor_pos, actor_delta
outputs actor_pos, actor_delta, pos
trashes a, y, z, n, c, v
{
ld y, 0
copy word 0, pos
repeat {
copy pos, actor_pos + y
copy word 40, actor_delta + y
st off, c
add pos, word 7
inc y
cmp y, 16
} until z
ld y, 0
copy word 0, actor_pos + y
copy word 0, actor_delta + y
}
// ----------------------------------------------------------------
// Actor Logics
// ----------------------------------------------------------------
//
// Sets carry if the player perished. Carry clear otherwise.
//
routine player_logic
inputs pos, delta, joy2, screen
outputs pos, delta, new_pos, screen, c
trashes a, x, y, z, n, v, ptr, compare_target
{
call read_stick
call calculate_new_position
call check_new_position_in_bounds
if c {
copy ^screen, ptr
st off, c
add ptr, new_pos
ld y, 0
// check collision.
copy [ptr] + y, a
// if "collision" is with your own self, treat it as if it's blank space!
cmp a, 81
if z {
ld a, 32
}
cmp a, 32
if z {
copy ^screen, ptr
st off, c
add ptr, pos
copy 32, [ptr] + y
copy new_pos, pos
copy ^screen, ptr
st off, c
add ptr, pos
copy 81, [ptr] + y
st off, c
} else {
st on, c
trash n
trash a
trash z
}
// FIXME these trashes, strictly speaking, probably shouldn't be needed,
// but currently the compiler cares too much about values that are
// initialized in one branch of an `if`, but not the other, but trashed
// at the end of the routine anyway.
trash ptr
trash y
trash a
trash v
} else {
st off, c
}
}
//
// Sets carry if the player perished. Carry clear otherwise.
//
routine enemy_logic
inputs pos, delta, screen
outputs pos, delta, new_pos, screen, c
trashes a, x, y, z, n, v, ptr, compare_target
{
call calculate_new_position
call check_new_position_in_bounds
if c {
copy ^screen, ptr
st off, c
add ptr, new_pos
ld y, 0
// check collision.
copy [ptr] + y, a
// if "collision" is with your own self, treat it as if it's blank space!
cmp a, 82
if z {
ld a, 32
}
cmp a, 32
if z {
copy ^screen, ptr
st off, c
add ptr, pos
copy 32, [ptr] + y
copy new_pos, pos
copy ^screen, ptr
st off, c
add ptr, pos
copy 82, [ptr] + y
st off, c
} else {
st on, c
trash n
trash a
trash z
}
// FIXME these trashes, strictly speaking, probably shouldn't be needed,
// but currently the compiler cares too much about values that are
// initialized in one branch of an `if`, but not the other, but trashed
// at the end of the routine anyway.
trash ptr
trash y
trash a
} else {
copy delta, compare_target
st on, c
sub compare_target, word 40
if not z {
copy word 40, delta
} else {
copy $ffd8, delta
}
trash compare_target
}
st off, c
}
// ----------------------------------------------------------------
// Game States
// ----------------------------------------------------------------
//
// Because these all `goto save_cinv` at the end, they must have the same signature as that routine.
//
routine game_state_title_screen
inputs joy2, button_down, press_fire_msg, dispatch_game_state, save_x,
actor_pos, pos, new_pos, actor_delta, delta,
screen, screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
outputs button_down, dispatch_game_state,
actor_pos, pos, new_pos, actor_delta, delta,
screen, screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
trashes a, x, y, c, z, n, v, ptr, save_x, compare_target
{
ld y, 0
repeat {
ld a, press_fire_msg + y
st on, c
sub a, 64 // yuck. oh well
st a, screen1 + y
inc y
cmp y, 18
} until z
st off, c
call check_button
if c {
call clear_screen
call init_game
copy forward game_state_play, dispatch_game_state
// FIXME these trashes, strictly speaking, probably shouldn't be needed,
// but currently the compiler cares too much about values that are
// initialized in one branch of an `if`, but not the other, but trashed
// at the end of the routine anyway.
trash a
trash n
trash z
} else {
trash y
trash c
trash v
}
goto save_cinv
}
routine game_state_play
inputs joy2, button_down, press_fire_msg, dispatch_game_state, save_x,
actor_pos, pos, new_pos, actor_delta, delta,
screen, screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
outputs button_down, dispatch_game_state,
actor_pos, pos, new_pos, actor_delta, delta,
screen, screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
trashes a, x, y, c, z, n, v, ptr, save_x, compare_target
{
ld x, 0
repeat {
copy actor_pos + x, pos
copy actor_delta + x, delta
st x, save_x
// FIXME need VECTOR TABLEs to make this happen:
// copy actor_logic, x dispatch_logic
// call indirect_jsr_logic
// For now, just check the actor ID to see what type it is, and go from there.
cmp x, 0
if z {
call player_logic
} else {
call enemy_logic
}
if c {
// Player died! Want no dead! Break out of the loop (this is a bit awkward.)
call clear_screen
copy forward game_state_game_over, dispatch_game_state
ld x, 15
st x, save_x
trash n
trash z
trash x
} else {
trash c
}
ld x, save_x
copy pos, actor_pos + x
copy delta, actor_delta + x
inc x
cmp x, 16
} until z
goto save_cinv
}
routine game_state_game_over
inputs joy2, button_down, press_fire_msg, dispatch_game_state, save_x,
actor_pos, pos, new_pos, actor_delta, delta,
screen, screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
outputs button_down, dispatch_game_state,
actor_pos, pos, new_pos, actor_delta, delta,
screen, screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
trashes a, x, y, c, z, n, v, ptr, save_x, compare_target
{
st off, c
call check_button
if c {
call clear_screen
call init_game
copy game_state_title_screen, dispatch_game_state
// FIXME these trashes, strictly speaking, probably shouldn't be needed,
// but currently the compiler cares too much about values that are
// initialized in one branch of an `if`, but not the other, but trashed
// at the end of the routine anyway.
trash a
trash n
trash z
} else {
trash y
trash c
trash v
}
goto save_cinv
}
// *************************
// * Main Game Loop Driver *
// *************************
routine our_cinv
inputs joy2, button_down, press_fire_msg, dispatch_game_state, save_x,
actor_pos, pos, new_pos, actor_delta, delta,
screen, screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
outputs button_down, dispatch_game_state,
actor_pos, pos, new_pos, actor_delta, delta,
screen, screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
trashes a, x, y, c, z, n, v, ptr, save_x, compare_target
{
goto dispatch_game_state
}
routine main
inputs cinv
outputs cinv, save_cinv, pos, dispatch_game_state,
screen1, screen2, screen3, screen4, colormap1, colormap2, colormap3, colormap4
trashes a, y, n, c, z, vic_border, vic_bg
{
ld a, 5
st a, vic_border
ld a, 0
st a, vic_bg
ld y, 0
call clear_screen
copy game_state_title_screen, dispatch_game_state
copy word 0, pos
with interrupts off {
copy cinv, save_cinv
copy our_cinv, cinv
}
repeat { } forever
}