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cvs_base: simplify star generator a bit (no difference here yet)

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hap 2024-11-28 15:56:52 +01:00
parent c6fc479ddb
commit cffaa099a9
2 changed files with 11 additions and 20 deletions
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29
src/mame/cvs/cvs_base.cpp
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@ -47,7 +47,7 @@ void cvs_base_state::scroll_start(int state)
void cvs_base_state::init_stars() void cvs_base_state::init_stars()
{ {
int generator = 0; uint32_t generator = 0;
m_total_stars = 0; m_total_stars = 0;
// precalculate the star background // precalculate the star background
@ -56,28 +56,20 @@ void cvs_base_state::init_stars()
for (int x = 511; x >= 0; x--) for (int x = 511; x >= 0; x--)
{ {
generator <<= 1; generator <<= 1;
int const bit1 = BIT(~generator, 17); generator |= BIT(~generator, 17) ^ BIT(generator, 5);
int const bit2 = BIT(generator, 5);
if (bit1 ^ bit2) if ((generator & 0x130fe) == 0xfe)
generator |= 1;
if (BIT(~generator, 16) && (generator & 0xfe) == 0xfe)
{ {
if (BIT(~generator, 12) && BIT(~generator, 13)) m_stars[m_total_stars].x = x;
{ m_stars[m_total_stars].y = y;
if (m_total_stars < CVS_MAX_STARS) m_stars[m_total_stars].code = 1;
{
m_stars[m_total_stars].x = x;
m_stars[m_total_stars].y = y;
m_stars[m_total_stars].code = 1;
m_total_stars++; m_total_stars++;
}
}
} }
} }
} }
assert(m_total_stars == 128);
} }
void cvs_base_state::update_stars(bitmap_ind16 &bitmap, const rectangle &cliprect, const pen_t star_pen, bool update_always) void cvs_base_state::update_stars(bitmap_ind16 &bitmap, const rectangle &cliprect, const pen_t star_pen, bool update_always)
@ -95,8 +87,7 @@ void cvs_base_state::update_stars(bitmap_ind16 &bitmap, const rectangle &cliprec
if (flip_screen_y()) if (flip_screen_y())
y = ~y; y = ~y;
if ((y >= cliprect.top()) && (y <= cliprect.bottom()) && if (cliprect.contains(x, y) && (update_always || (m_palette->pen_indirect(bitmap.pix(y, x)) == 0)))
(update_always || (m_palette->pen_indirect(bitmap.pix(y, x)) == 0)))
bitmap.pix(y, x) = star_pen; bitmap.pix(y, x) = star_pen;
} }
} }

2
src/mame/cvs/cvs_base.h
View File

@ -38,7 +38,7 @@ protected:
, m_ram_view(*this, "video_color_ram_view") , m_ram_view(*this, "video_color_ram_view")
{ } { }
static inline constexpr uint8_t CVS_MAX_STARS = 250; static inline constexpr uint8_t CVS_MAX_STARS = 128;
static inline constexpr int8_t CVS_S2636_Y_OFFSET = -5; static inline constexpr int8_t CVS_S2636_Y_OFFSET = -5;
static inline constexpr int8_t CVS_S2636_X_OFFSET = -26; static inline constexpr int8_t CVS_S2636_X_OFFSET = -26;