From 60e77785e8c528f053048e0dcc6f571d73209cee Mon Sep 17 00:00:00 2001 From: Thomas Harte Date: Mon, 22 Mar 2021 22:34:28 -0400 Subject: [PATCH] Makes an attempt to provide the necessary hook for floating bus behaviour. --- Machines/Sinclair/ZXSpectrum/Video.hpp | 95 ++++++++++++++------------ 1 file changed, 50 insertions(+), 45 deletions(-) diff --git a/Machines/Sinclair/ZXSpectrum/Video.hpp b/Machines/Sinclair/ZXSpectrum/Video.hpp index cf24ba3a8..037165c4f 100644 --- a/Machines/Sinclair/ZXSpectrum/Video.hpp +++ b/Machines/Sinclair/ZXSpectrum/Video.hpp @@ -158,53 +158,40 @@ template class Video { const int start_column = offset >> 4; const int end_column = (offset + pixel_duration) >> 4; for(int column = start_column; column < end_column; column++) { - const uint8_t attributes[2] = { - memory_[attribute_address_], - memory_[attribute_address_+1], - }; - - constexpr uint8_t masks[] = {0, 0xff}; - const uint8_t pixels[2] = { - uint8_t(memory_[pixel_address_] ^ masks[flash_mask_ & (attributes[0] >> 7)]), - uint8_t(memory_[pixel_address_+1] ^ masks[flash_mask_ & (attributes[1] >> 7)]), - }; - - { - const uint8_t colours[2] = { - palette[(attributes[0] & 0x78) >> 3], - palette[((attributes[0] & 0x40) >> 3) | (attributes[0] & 0x07)], - }; - - pixel_target_[0] = colours[(pixels[0] >> 7) & 1]; - pixel_target_[1] = colours[(pixels[0] >> 6) & 1]; - pixel_target_[2] = colours[(pixels[0] >> 5) & 1]; - pixel_target_[3] = colours[(pixels[0] >> 4) & 1]; - pixel_target_[4] = colours[(pixels[0] >> 3) & 1]; - pixel_target_[5] = colours[(pixels[0] >> 2) & 1]; - pixel_target_[6] = colours[(pixels[0] >> 1) & 1]; - pixel_target_[7] = colours[(pixels[0] >> 0) & 1]; - pixel_target_ += 8; - } - - { - const uint8_t colours[2] = { - palette[(attributes[1] & 0x78) >> 3], - palette[((attributes[1] & 0x40) >> 3) | (attributes[1] & 0x07)], - }; - - pixel_target_[0] = colours[(pixels[1] >> 7) & 1]; - pixel_target_[1] = colours[(pixels[1] >> 6) & 1]; - pixel_target_[2] = colours[(pixels[1] >> 5) & 1]; - pixel_target_[3] = colours[(pixels[1] >> 4) & 1]; - pixel_target_[4] = colours[(pixels[1] >> 3) & 1]; - pixel_target_[5] = colours[(pixels[1] >> 2) & 1]; - pixel_target_[6] = colours[(pixels[1] >> 1) & 1]; - pixel_target_[7] = colours[(pixels[1] >> 0) & 1]; - pixel_target_ += 8; - } - + last_fetches_[0] = memory_[pixel_address_]; + last_fetches_[1] = memory_[attribute_address_]; + last_fetches_[2] = memory_[pixel_address_+1]; + last_fetches_[3] = memory_[attribute_address_+1]; pixel_address_ += 2; attribute_address_ += 2; + + constexpr uint8_t masks[] = {0, 0xff}; + +#define Output(n) \ + { \ + const uint8_t pixels = \ + uint8_t(last_fetches_[n] ^ masks[flash_mask_ & (last_fetches_[n+1] >> 7)]); \ + \ + const uint8_t colours[2] = { \ + palette[(last_fetches_[n+1] & 0x78) >> 3], \ + palette[((last_fetches_[n+1] & 0x40) >> 3) | (last_fetches_[n+1] & 0x07)], \ + }; \ + \ + pixel_target_[0] = colours[(pixels >> 7) & 1]; \ + pixel_target_[1] = colours[(pixels >> 6) & 1]; \ + pixel_target_[2] = colours[(pixels >> 5) & 1]; \ + pixel_target_[3] = colours[(pixels >> 4) & 1]; \ + pixel_target_[4] = colours[(pixels >> 3) & 1]; \ + pixel_target_[5] = colours[(pixels >> 2) & 1]; \ + pixel_target_[6] = colours[(pixels >> 1) & 1]; \ + pixel_target_[7] = colours[(pixels >> 0) & 1]; \ + pixel_target_ += 8; \ + } + + Output(0); + Output(2); + +#undef Output } } @@ -322,6 +309,22 @@ template class Video { return timings.delays[time_into_line & 15]; } + /*! + @returns Whatever the ULA or gate array has fetched this cycle, or 0xff if it has fetched nothing. + */ + uint8_t get_current_fetch() const { + constexpr auto timings = get_timings(); + const int line = time_into_frame_ / timings.cycles_per_line; + if(line >= 192) return 0xff; + + const int time_into_line = time_into_frame_ % timings.cycles_per_line; + if(time_into_line >= 256 || (time_into_line&4)) { + return 0xff; + } + + return last_fetches_[time_into_line & 3]; + } + /*! Sets the current border colour. */ @@ -358,6 +361,8 @@ template class Video { int flash_counter_ = 0; bool is_alternate_line_ = false; + uint8_t last_fetches_[4] = {0xff, 0xff, 0xff, 0xff}; + #define RGB(r, g, b) (r << 4) | (g << 2) | b static constexpr uint8_t palette[] = { RGB(0, 0, 0), RGB(0, 0, 2), RGB(2, 0, 0), RGB(2, 0, 2),