6502/CLK
1
0
Fork 0
mirror of https://github.com/TomHarte/CLK.git synced 2026-04-26 19:17:52 +00:00
Code Issues Projects Releases Wiki Activity

Edges to within millimetres of CRAM dots.

Browse Source 
... but all the way up to bedtime.
This commit is contained in:
Thomas Harte
2018-10-25 23:12:03 -04:00
parent 9621ba59ae
commit 0587b9f257
2 changed files with 43 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files
Components/9918/Implementation/9918Base.hpp
+25 -5
View File
@@ -253,6 +253,16 @@ class Base {
int row, column;
} read_pointer_, write_pointer_;
// The SMS VDP has a programmer-set colour palette, with a dedicated patch of RAM. But the RAM is only exactly
// fast enough for the pixel clock. So when the programmer writes to it, that causes a one-pixel glitch; there
// isn't the bandwidth for the read both write to occur simultaneously. The following buffer therefore keeps
// track of pending collisions, for visual reproduction.
struct CRAMDot {
LineBufferPointer location;
uint32_t value;
};
std::vector<CRAMDot> upcoming_cram_dots_;
// Extra information that affects the Master System output mode.
struct {
// Programmer-set flags.
@@ -314,17 +324,27 @@ class Base {
screen_mode_ = ScreenMode::Blank;
}
void do_external_slot() {
void do_external_slot(int access_column) {
// TODO: is queued access ready yet?
switch(queued_access_) {
default: return;
case MemoryAccess::Write:
if(master_system_.cram_is_selected) {
// Adjust the palette.
master_system_.colour_ram[ram_pointer_ & 0x1f] = palette_pack(
static_cast<uint8_t>(((read_ahead_buffer_ >> 0) & 3) * 255 / 3),
static_cast<uint8_t>(((read_ahead_buffer_ >> 2) & 3) * 255 / 3),
static_cast<uint8_t>(((read_ahead_buffer_ >> 4) & 3) * 255 / 3)
);
// Schedule a CRAM dot.
upcoming_cram_dots_.emplace_back();
auto dot = upcoming_cram_dots_.back();
dot.location.row = write_pointer_.row;
dot.location.column = access_column;
dot.value = master_system_.colour_ram[ram_pointer_ & 0x1f];
} else {
ram_[ram_pointer_ & 16383] = read_ahead_buffer_;
}
@@ -374,7 +394,7 @@ class Base {
case n
#define external_slot(n) \
slot(n): do_external_slot();
slot(n): do_external_slot((n)*2);
#define external_slots_2(n) \
external_slot(n); \
@@ -606,7 +626,7 @@ class Base {
slot(31):
sprite_selection_buffer.reset_sprite_collection();
do_external_slot();
do_external_slot(31*2);
external_slots_2(32);
external_slot(34);
@@ -758,7 +778,7 @@ class Base {
slot(29):
sprite_selection_buffer.reset_sprite_collection();
do_external_slot();
do_external_slot(29*2);
external_slot(30);
sprite_y_read(31, 0);
@@ -799,7 +819,7 @@ class Base {
bool asked_for_write_area_ = false;
void draw_tms_character(int start, int end);
void draw_tms_text(int start, int end);
void draw_sms(int start, int end);
void draw_sms(int start, int end, uint32_t cram_dot);
};
}