JIT: implement timer support in mtspr

Faster, of course, since we avoid the interpreter, but also means we can
get more a more accurate timer in long blocks by adding the offset from the
start of the block to the retrieved timer. I don't know if this will actually
fix any issues, but it's more correct and a nearly-free improvement.
This commit is contained in:
Fiora
2014-08-19 21:52:09 -07:00
parent e10b0d1008
commit 816d056657
3 changed files with 49 additions and 28 deletions

View File

@ -70,31 +70,6 @@ namespace SystemTimers
static u32 CPU_CORE_CLOCK = 486000000u; // 486 mhz (its not 485, stop bugging me!)
/*
GameCube MHz
flipper <-> ARAM bus: 81 (DSP)
gekko <-> flipper bus: 162
flipper <-> 1T-SRAM bus: 324
gekko: 486
These contain some guesses:
Wii MHz
hollywood <-> GDDR3 RAM bus: ??? no idea really
broadway <-> hollywood bus: 243
hollywood <-> 1T-SRAM bus: 486
broadway: 729
*/
// Ratio of TB and Decrementer to clock cycles.
// TB clk is 1/4 of BUS clk. And it seems BUS clk is really 1/3 of CPU clk.
// So, ratio is 1 / (1/4 * 1/3 = 1/12) = 12.
// note: ZWW is ok and faster with TIMER_RATIO=8 though.
// !!! POSSIBLE STABLE PERF BOOST HACK THERE !!!
enum
{
TIMER_RATIO = 12
};
static int et_Dec;
static int et_VI;
static int et_SI;