bsnes/higan/sfc/cpu/irq.cpp
Tim Allen 82293c95ae Update to v099r14 release.
byuu says:

Changelog:
- (u)int(max,ptr) abbreviations removed; use _t suffix now [didn't feel
  like they were contributing enough to be worth it]
- cleaned up nall::integer,natural,real functionality
  - toInteger, toNatural, toReal for parsing strings to numbers
  - fromInteger, fromNatural, fromReal for creating strings from numbers
  - (string,Markup::Node,SQL-based-classes)::(integer,natural,real)
    left unchanged
  - template<typename T> numeral(T value, long padding, char padchar)
    -> string for print() formatting
    - deduces integer,natural,real based on T ... cast the value if you
      want to override
    - there still exists binary,octal,hex,pointer for explicit print()
      formatting
- lstring -> string_vector [but using lstring = string_vector; is
  declared]
  - would be nice to remove the using lstring eventually ... but that'd
    probably require 10,000 lines of changes >_>
- format -> string_format [no using here; format was too ambiguous]
- using integer = Integer<sizeof(int)*8>; and using natural =
  Natural<sizeof(uint)*8>; declared
  - for consistency with boolean. These three are meant for creating
    zero-initialized values implicitly (various uses)
- R65816::io() -> idle() and SPC700::io() -> idle() [more clear; frees
  up struct IO {} io; naming]
- SFC CPU, PPU, SMP use struct IO {} io; over struct (Status,Registers) {}
  (status,registers); now
  - still some CPU::Status status values ... they didn't really fit into
    IO functionality ... will have to think about this more
- SFC CPU, PPU, SMP now use step() exclusively instead of addClocks()
  calling into step()
- SFC CPU joypad1_bits, joypad2_bits were unused; killed them
- SFC PPU CGRAM moved into PPU::Screen; since nothing else uses it
- SFC PPU OAM moved into PPU::Object; since nothing else uses it
  - the raw uint8[544] array is gone. OAM::read() constructs values from
    the OAM::Object[512] table now
  - this avoids having to determine how we want to sub-divide the two
    OAM memory sections
  - this also eliminates the OAM::synchronize() functionality
- probably more I'm forgetting

The FPS fluctuations are driving me insane. This WIP went from 128fps to
137fps. Settled on 133.5fps for the final build. But nothing I changed
should have affected performance at all. This level of fluctuation makes
it damn near impossible to know whether I'm speeding things up or slowing
things down with changes.
2016-07-01 21:50:32 +10:00

103 lines
2.6 KiB
C++

//called once every four clock cycles;
//as NMI steps by scanlines (divisible by 4) and IRQ by PPU 4-cycle dots.
//
//ppu.(vh)counter(n) returns the value of said counters n-clocks before current time;
//it is used to emulate hardware communication delay between opcode and interrupt units.
auto CPU::pollInterrupts() -> void {
//NMI hold
if(status.nmiHold) {
status.nmiHold = false;
if(io.nmiEnabled) status.nmiTransition = true;
}
//NMI test
bool nmiValid = vcounter(2) >= ppu.vdisp();
if(!status.nmiValid && nmiValid) {
//0->1 edge sensitive transition
status.nmiLine = true;
status.nmiHold = true; //hold /NMI for four cycles
} else if(status.nmiValid && !nmiValid) {
//1->0 edge sensitive transition
status.nmiLine = false;
}
status.nmiValid = nmiValid;
//IRQ hold
status.irqHold = false;
if(status.irqLine) {
if(io.virqEnabled || io.hirqEnabled) status.irqTransition = true;
}
//IRQ test
bool irqValid = io.virqEnabled || io.hirqEnabled;
if(irqValid) {
if((io.virqEnabled && vcounter(10) != (io.virqPos))
|| (io.hirqEnabled && hcounter(10) != (io.hirqPos + 1) * 4)
|| (io.virqPos && vcounter(6) == 0) //IRQs cannot trigger on last dot of field
) irqValid = false;
}
if(!status.irqValid && irqValid) {
//0->1 edge sensitive transition
status.irqLine = true;
status.irqHold = true; //hold /IRQ for four cycles
}
status.irqValid = irqValid;
}
auto CPU::nmitimenUpdate(uint8 data) -> void {
bool nmiEnabled = io.nmiEnabled;
bool virqEnabled = io.virqEnabled;
bool hirqEnabled = io.hirqEnabled;
io.nmiEnabled = data & 0x80;
io.virqEnabled = data & 0x20;
io.hirqEnabled = data & 0x10;
//0->1 edge sensitive transition
if(!nmiEnabled && io.nmiEnabled && status.nmiLine) {
status.nmiTransition = true;
}
//?->1 level sensitive transition
if(io.virqEnabled && !io.hirqEnabled && status.irqLine) {
status.irqTransition = true;
}
if(!io.virqEnabled && !io.hirqEnabled) {
status.irqLine = false;
status.irqTransition = false;
}
status.irqLock = true;
}
auto CPU::rdnmi() -> bool {
bool result = status.nmiLine;
if(!status.nmiHold) {
status.nmiLine = false;
}
return result;
}
auto CPU::timeup() -> bool {
bool result = status.irqLine;
if(!status.irqHold) {
status.irqLine = false;
status.irqTransition = false;
}
return result;
}
auto CPU::nmiTest() -> bool {
if(!status.nmiTransition) return false;
status.nmiTransition = false;
r.wai = false;
return true;
}
auto CPU::irqTest() -> bool {
if(!status.irqTransition && !r.irq) return false;
status.irqTransition = false;
r.wai = false;
return !r.p.i;
}