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This mapping needs to know where it will occur.

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This commit is contained in:
Thomas Harte 2021-06-27 17:30:09 -04:00
parent 81e9ba5608
commit be19fa9dde
2 changed files with 23 additions and 8 deletions
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4
ClockReceiver/JustInTime.hpp
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@ -205,8 +205,8 @@ template <class T, class LocalTimeScale = HalfCycles, int multiplier = 1, int di
}
/// Indicates the amount of time, in the local time scale, until the first local slot that falls wholly
/// after the amount of time provided in the target time scale.
[[nodiscard]] forceinline LocalTimeScale back_map(TargetTimeScale time) const {
/// after @c duration, if that delay were to occur in @c offset units of time from now.
[[nodiscard]] forceinline LocalTimeScale back_map(TargetTimeScale duration, TargetTimeScale offset) const {
// TODO.
return LocalTimeScale(0);
}

27
Machines/Enterprise/Enterprise.cpp
View File

@ -237,6 +237,18 @@ template <bool has_disk_controller> class ConcreteMachine:
const uint16_t address = cycle.address ? *cycle.address : 0x0000;
// Calculate an access penalty, if applicable.
//
// Rule applied here, which is slightly inferred:
//
// Non-video reads and writes are delayed by exactly a cycle or not delayed at all,
// depending on the programmer's configuration of Dave.
//
// Video reads and writes, and Nick port accesses, are delayed so that the last
// clock cycle of the machine cycle falls wholly inside the designated Z80 access
// window, per Nick.
//
// The switch statement below just attempts to implement that logic.
//
HalfCycles penalty;
switch(cycle.operation) {
default: break;
@ -254,8 +266,9 @@ template <bool has_disk_controller> class ConcreteMachine:
} else {
// Query Nick for the amount of delay that would occur with one cycle left
// in this read opcode.
const auto delay = nick_.last_valid()->get_time_until_z80_slot(nick_.time_since_flush(HalfCycles(2)));
penalty = nick_.back_map(delay);
const auto delay_time = nick_.time_since_flush(HalfCycles(2));
const auto delay = nick_.last_valid()->get_time_until_z80_slot(delay_time);
penalty = nick_.back_map(delay, delay_time);
}
break;
@ -272,8 +285,9 @@ template <bool has_disk_controller> class ConcreteMachine:
if(is_video_[address >> 14]) {
// Get delay, in Nick cycles, for a Z80 access that occurs in 0.5
// cycles from now (i.e. with one cycle left to run).
const auto delay = nick_.last_valid()->get_time_until_z80_slot(nick_.time_since_flush(HalfCycles(1)));
penalty = nick_.back_map(delay);
const auto delay_time = nick_.time_since_flush(HalfCycles(1));
const auto delay = nick_.last_valid()->get_time_until_z80_slot(delay_time);
penalty = nick_.back_map(delay, delay_time);
}
break;
@ -282,8 +296,9 @@ template <bool has_disk_controller> class ConcreteMachine:
if((address & 0xf0) == 0x80) {
// Get delay, in Nick cycles, for a Z80 access that occurs in 0.5
// cycles from now (i.e. with one cycle left to run).
const auto delay = nick_.last_valid()->get_time_until_z80_slot(nick_.time_since_flush(HalfCycles(1)));
penalty = nick_.back_map(delay);
const auto delay_time = nick_.time_since_flush(HalfCycles(1));
const auto delay = nick_.last_valid()->get_time_until_z80_slot(delay_time);
penalty = nick_.back_map(delay, delay_time);
}
}
}