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tugboat: no need to latch fine scroll

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This commit is contained in:
hap 2023-08-07 12:51:20 +02:00
parent 5f2a611553
commit ae2eb005fa
1 changed files with 17 additions and 50 deletions
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67
src/mame/misc/tugboat.cpp
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@ -11,8 +11,6 @@ TODO:
- check how the score is displayed. I'm quite sure that score_w is supposed to
access videoram scanning it by columns (like btime_mirrorvideoram_w), but
the current implementation is a big kludge.
- why is fine x scroll latched differently for noahsark? or is something wrong
with IRQ timing that causes it to dislike how tugboat does it?
- colors might not be entirely accurate
Suspect berenstn is using the wrong color PROM.
- convert to use the HD46505 device, it has two.
@ -106,10 +104,8 @@ private:
u8 m_hd46505_reglatch[2] = { };
u16 m_start_address[2] = { };
u8 m_control[2] = { };
u8 m_fine_x_clock = 0;
u8 m_fine_y_clock = 0;
u8 m_fine_x_latch = 0;
u8 m_fine_y_latch = 0;
u8 m_fine_x = 0;
u8 m_fine_y = 0;
template<int N> void hd46505_w(offs_t offset, u8 data);
void score_w(offs_t offset, u8 data);
@ -117,12 +113,8 @@ private:
void control0_w(offs_t offset, u8 data, u8 mem_mask);
void control1_w(offs_t offset, u8 data, u8 mem_mask);
void latch_start_address();
void tugboat_vblank_w(int state);
void noahsark_vblank_w(int state);
void tugboat_palette(palette_device &palette) const;
void vblank_w(int state);
u32 screen_update(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect);
void draw_tilemap(bitmap_ind16 &bitmap, const rectangle &cliprect, int layer);
@ -143,10 +135,8 @@ void tugboat_state::machine_start()
save_item(NAME(m_hd46505_reglatch));
save_item(NAME(m_start_address));
save_item(NAME(m_control));
save_item(NAME(m_fine_x_clock));
save_item(NAME(m_fine_y_clock));
save_item(NAME(m_fine_x_latch));
save_item(NAME(m_fine_y_latch));
save_item(NAME(m_fine_x));
save_item(NAME(m_fine_y));
}
void tugboat_state::video_start()
@ -188,36 +178,13 @@ void tugboat_state::hd46505_w(offs_t offset, u8 data)
m_hd46505_regs[N][m_hd46505_reglatch[N]] = data;
}
void tugboat_state::latch_start_address()
{
// crtc display start address is latched at end of visarea
for (int i = 0; i < 2; i++)
m_start_address[i] = m_hd46505_regs[i][0x0c] << 8 | m_hd46505_regs[i][0x0d];
}
void tugboat_state::tugboat_vblank_w(int state)
void tugboat_state::vblank_w(int state)
{
if (state)
{
latch_start_address();
}
else
{
m_fine_x_latch = m_fine_x_clock;
m_fine_y_latch = m_fine_y_clock;
}
}
void tugboat_state::noahsark_vblank_w(int state)
{
if (state)
{
latch_start_address();
m_fine_x_latch = m_fine_x_clock;
}
else
{
m_fine_y_latch = m_fine_y_clock;
// latch display start address
for (int i = 0; i < 2; i++)
m_start_address[i] = m_hd46505_regs[i][0x0c] << 8 | m_hd46505_regs[i][0x0d];
}
}
@ -248,10 +215,10 @@ void tugboat_state::draw_tilemap(bitmap_ind16 &bitmap, const rectangle &cliprect
// score panel column doesn't scroll
if (x != 29)
fy = m_fine_y_latch;
fy = m_fine_y;
}
else
fx = m_fine_x_latch;
fx = m_fine_x;
m_gfxdecode->gfx(rgn)->transpen(bitmap,cliprect,
code,
@ -305,11 +272,11 @@ void tugboat_state::control0_w(offs_t offset, u8 data, u8 mem_mask)
// d6: clock layer 1 fine x scroll
if (data & ~m_control[0] & 0x40)
m_fine_x_clock = (m_fine_x_clock + 1) & 7;
m_fine_x = (m_fine_x + 1) & 7;
// d7: clear layer 1 fine x scroll
if (data & 0x80)
m_fine_x_clock = 0;
m_fine_x = 0;
m_control[0] = data;
}
@ -321,11 +288,11 @@ void tugboat_state::control1_w(offs_t offset, u8 data, u8 mem_mask)
// d2: clock layer 2 fine y scroll
if (data & ~m_control[1] & 4)
m_fine_y_clock = (m_fine_y_clock + 1) & 7;
m_fine_y = (m_fine_y + 1) & 7;
// d0: clear layer 2 fine y scroll
if (data & 1)
m_fine_y_clock = 0;
m_fine_y = 0;
// d4-d7: input select
m_control[1] = data;
@ -468,7 +435,7 @@ void tugboat_state::tugboat(machine_config &config)
m_screen->set_screen_update(FUNC(tugboat_state::screen_update));
m_screen->set_palette(m_palette);
m_screen->screen_vblank().set(m_pia[1], FUNC(pia6821_device::cb1_w));
m_screen->screen_vblank().append(FUNC(tugboat_state::tugboat_vblank_w));
m_screen->screen_vblank().append(FUNC(tugboat_state::vblank_w));
GFXDECODE(config, m_gfxdecode, m_palette, gfx_tugboat);
PALETTE(config, m_palette, FUNC(tugboat_state::tugboat_palette), 256);
@ -485,7 +452,7 @@ void tugboat_state::noahsark(machine_config &config)
// video hardware
m_screen->screen_vblank().set(m_pia[1], FUNC(pia6821_device::cb1_w));
m_screen->screen_vblank().append(FUNC(tugboat_state::noahsark_vblank_w));
m_screen->screen_vblank().append(FUNC(tugboat_state::vblank_w)).invert();
}