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Improve constness, primarily of reverse_table.

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Thomas Harte
2022-12-29 11:29:19 -05:00
parent 5ba97da6cd
commit 5d89293c92
1 changed files with 24 additions and 18 deletions
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42
Components/9918/9918.cpp
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@@ -62,23 +62,29 @@ constexpr unsigned int CRTCyclesPerLine = 1365;
constexpr unsigned int CRTCyclesDivider = 4; constexpr unsigned int CRTCyclesDivider = 4;
struct ReverseTable { struct ReverseTable {
std::uint8_t map[256]; const std::array<uint8_t, 256> map;
constexpr ReverseTable() : map(reverse_table()) {}
ReverseTable() { private:
for(int c = 0; c < 256; ++c) { static constexpr std::array<uint8_t, 256> reverse_table() {
map[c] = uint8_t( std::array<uint8_t, 256> map{};
((c & 0x80) >> 7) | for(size_t c = 0; c < 256; ++c) {
((c & 0x40) >> 5) | map[c] = uint8_t(
((c & 0x20) >> 3) | ((c & 0x80) >> 7) |
((c & 0x10) >> 1) | ((c & 0x40) >> 5) |
((c & 0x08) << 1) | ((c & 0x20) >> 3) |
((c & 0x04) << 3) | ((c & 0x10) >> 1) |
((c & 0x02) << 5) | ((c & 0x08) << 1) |
((c & 0x01) << 7) ((c & 0x04) << 3) |
); ((c & 0x02) << 5) |
((c & 0x01) << 7)
);
}
return map;
} }
} };
} reverse_table;
constexpr ReverseTable reverse_table;
} }
@@ -515,7 +521,7 @@ void TMS9918::run_for(const HalfCycles cycles) {
void Base::output_border(int cycles, uint32_t cram_dot) { void Base::output_border(int cycles, uint32_t cram_dot) {
cycles *= 4; cycles *= 4;
uint32_t border_colour = const uint32_t border_colour =
is_sega_vdp(personality_) ? is_sega_vdp(personality_) ?
master_system_.colour_ram[16 + background_colour_] : master_system_.colour_ram[16 + background_colour_] :
palette[background_colour_]; palette[background_colour_];
@@ -728,13 +734,13 @@ uint8_t TMS9918::read(int address) {
// Reads from address 0 read video RAM, via the read-ahead buffer. // Reads from address 0 read video RAM, via the read-ahead buffer.
if(!(address & 1)) { if(!(address & 1)) {
// Enqueue the write to occur at the next available slot. // Enqueue the write to occur at the next available slot.
uint8_t result = read_ahead_buffer_; const uint8_t result = read_ahead_buffer_;
queued_access_ = MemoryAccess::Read; queued_access_ = MemoryAccess::Read;
return result; return result;
} }
// Reads from address 1 get the status register. // Reads from address 1 get the status register.
uint8_t result = status_; const uint8_t result = status_;
status_ &= ~(StatusInterrupt | StatusSpriteOverflow | StatusSpriteCollision); status_ &= ~(StatusInterrupt | StatusSpriteOverflow | StatusSpriteCollision);
line_interrupt_pending_ = false; line_interrupt_pending_ = false;
return result; return result;