From c0fe88a5bbfb0bda329b59e41d80a22d0a00b400 Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 9 Jan 2023 13:54:49 -0500
Subject: [PATCH] Apply clock conversion to existing usages of
do_external_slot.
---
.../9918/Implementation/ClockConverter.hpp | 18 ++++++++++++++++++
Components/9918/Implementation/Fetch.hpp | 12 +++---------
2 files changed, 21 insertions(+), 9 deletions(-)
diff --git a/Components/9918/Implementation/ClockConverter.hpp b/Components/9918/Implementation/ClockConverter.hpp
index f6ae33bd5..ce7f50657 100644
--- a/Components/9918/Implementation/ClockConverter.hpp
+++ b/Components/9918/Implementation/ClockConverter.hpp
@@ -182,6 +182,24 @@ template <Personality personality> class ClockConverter {
}
}
+ /*!
+ Converts a position in TMS access cycles back to one at the native
+ clock rate.
+ */
+ static constexpr int from_tms_access_clock(int source) {
+ switch(personality) {
+ default:
+ return source << 1;
+
+ case Personality::V9938:
+ case Personality::V9958:
+ return source << 3;
+
+ case Personality::MDVDP:
+ return source * 20;
+ }
+ }
+
/*!
Converts a position in internal cycles to its corresponding position
on the TMS pixel clock, i.e. scales to 342 clocks per line.
diff --git a/Components/9918/Implementation/Fetch.hpp b/Components/9918/Implementation/Fetch.hpp
index 03c3d9478..c44ab0822 100644
--- a/Components/9918/Implementation/Fetch.hpp
+++ b/Components/9918/Implementation/Fetch.hpp
@@ -41,19 +41,13 @@
for the exceptions.
*/
-// TODO: external_slot needs to do a proper conversion back to the internal clock,
-// not assume a multiply by two.
-//
-// (and, for MSX 2 purposes, it would ideally know how many cycles since the last access
-// slot, probably, but I'm not completely sure that's necessary yet)
-
#define slot(n) \
if(use_end && end == n) return; \
[[fallthrough]]; \
case n
#define external_slot(n) \
- slot(n): do_external_slot((n)*2);
+ slot(n): do_external_slot(clock_converter_.from_tms_access_clock(n));
#define external_slots_2(n) \
external_slot(n); \
@@ -286,7 +280,7 @@ template<bool use_end> void Base<personality>::fetch_tms_character(int start, in
slot(31):
sprite_selection_buffer.reset_sprite_collection();
- do_external_slot(31*2);
+ do_external_slot(clock_converter_.from_tms_access_clock(31));
external_slots_2(32);
external_slot(34);
@@ -437,7 +431,7 @@ template<bool use_end> void Base<personality>::fetch_sms(int start, int end) {
slot(29):
sprite_selection_buffer.reset_sprite_collection();
- do_external_slot(29*2);
+ do_external_slot(clock_converter_.from_tms_access_clock(29));
external_slot(30);
sprite_y_read(31, 0);