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https://github.com/mauiaaron/apple2.git
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WIP : dynamically adjustable spinloop
This commit is contained in:
Aaron Culliney
parent
da3a78a295
commit
980bcc627d
128
src/timing.c
128
src/timing.c
@ -10,32 +10,26 @@
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*
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*/
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#include "timing.h"
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#include "misc.h"
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#include <stdlib.h>
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#include <stdio.h>
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#include <stdint.h>
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#include <time.h>
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#include <pthread.h>
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#include <limits.h>
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#define CALIBRATE_HZ 120
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#include "timing.h"
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#include "misc.h"
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#include "cpu.h"
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static unsigned long cpu_target_hz = APPLE2_HZ; // target clock speed
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static unsigned long calibrate_interval = NANOSECONDS / CALIBRATE_HZ; // calibration interval for drifting
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static unsigned long cycle_nanoseconds = NANOSECONDS / APPLE2_HZ; // nanosecs per cycle
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static unsigned int cycle_nanoseconds_count;
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#define CALIBRATE_HZ 100
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static struct timespec deltat, t0, ti, tj;
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static unsigned long CPU_TARGET_HZ = APPLE2_HZ; // target clock speed
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static unsigned long CALIBRATE_INTERVAL = NANOSECONDS / CALIBRATE_HZ; // calibration interval for drifting
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static float CYCLE_NSECS = NANOSECONDS / (float)APPLE2_HZ; // nanosecs per cycle
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static unsigned long cycle_count=0; // CPU cycle counter
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static int spinloop_count=0; // spin loop counter
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static struct timespec ti;
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static long sleep_adjust=0;
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static long sleep_adjust_inc=0;
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extern pthread_mutex_t mutex;
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extern pthread_cond_t cond;
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static int spinloop_count=0; // spin loop counter
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// -----------------------------------------------------------------------------
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@ -74,7 +68,7 @@ static inline void _spin_loop(unsigned long c)
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static void _determine_initial_spinloop_counter()
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{
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struct timespec s0, s1;
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struct timespec s0, s1, deltat;
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// time the spinloop to determine a good starting value for the spin counter
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@ -106,11 +100,9 @@ static void _determine_initial_spinloop_counter()
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avg_spin_nsecs = (avg_spin_nsecs / samples);
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printf("average = %lu nsec\n", avg_spin_nsecs);
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spinloop_count = cycle_nanoseconds * spinloop_count / avg_spin_nsecs;
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spinloop_count = CYCLE_NSECS * spinloop_count / avg_spin_nsecs;
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cycle_nanoseconds_count = cycle_nanoseconds / spinloop_count;
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printf("counter for a single cycle = %d\n", spinloop_count);
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printf("counter for a single %fns cycle = %d\n", CYCLE_NSECS, spinloop_count);
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}
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void timing_initialize() {
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@ -118,8 +110,7 @@ void timing_initialize() {
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// should do this only on startup
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_determine_initial_spinloop_counter();
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clock_gettime(CLOCK_MONOTONIC, &t0);
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ti=t0;
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clock_gettime(CLOCK_MONOTONIC, &ti);
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}
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void timing_set_cpu_scale(unsigned int scale)
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@ -128,71 +119,64 @@ void timing_set_cpu_scale(unsigned int scale)
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}
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/*
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* Throttles 6502 CPU down to the target CPU frequency (default is speed of original Apple //e).
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*
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* This uses an adaptive spin loop to stay closer to the target CPU frequency.
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* Calibrate emulator clock to real clock ...
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*
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* NOTE: these calculations could overflow if emulator speed is severely dampened back...
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*/
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void timing_throttle()
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static int _calibrate_clock (long drift_interval_nsecs)
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{
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static unsigned int drift_interval_counter=0; // in nsecs since last
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static unsigned int instruction_interval_counter=0; // instruction count since last
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static unsigned int spin_adjust_interval=INT_MAX;
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static int8_t spin_adjust_count=0; // +/- 1
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++instruction_interval_counter;
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unsigned int opcycles = cpu65__opcycles[cpu65_debug.opcode] + cpu65_debug.opcycles;
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if (!opcycles)
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{
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opcycles = 2; // assume 2 cycles for UNK opcodes
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}
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cycle_count += opcycles;
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int8_t c = instruction_interval_counter%spin_adjust_interval ? spin_adjust_count : 0;
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_spin_loop(opcycles * (spinloop_count + c) );
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drift_interval_counter += c*cycle_nanoseconds;
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if (drift_interval_counter < calibrate_interval)
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{
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return;
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}
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// -------------------------------------------------------------------------
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// calibrate emulator clock to real clock ...
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return 0;
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// HACK FIXME : this is broken, plz debug, kthxbye!
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struct timespec tj, deltat;
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clock_gettime(CLOCK_MONOTONIC, &tj);
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deltat = timespec_diff(ti, tj);
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ti=tj;
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// NOTE: these calculations could overflow if emulator speed is severely dampened back...
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unsigned long real_counter = NANOSECONDS * deltat.tv_sec;
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real_counter += deltat.tv_nsec;
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long diff_nsecs = real_counter - drift_interval_counter; // whole +/- nsec diff
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long real_nsecs = NANOSECONDS * deltat.tv_sec + deltat.tv_nsec;
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int drift_nsecs = (int)(drift_interval_nsecs - real_nsecs); // +/- nsec drift
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int drift_count = (int)(drift_nsecs * (spinloop_count / CYCLE_NSECS) ); // +/- count drift
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float nsecs_per_oneloop = cycle_nanoseconds/(float)spinloop_count;
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unsigned int instruction_interval_nsecs = instruction_interval_counter * nsecs_per_oneloop;
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// adjust spinloop_count ...
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spinloop_count += drift_count / CALIBRATE_INTERVAL;
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// reset
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drift_interval_counter=0;
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instruction_interval_counter=0;
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// ideally we should return a sub-interval here ...
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return 0;
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}
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// calculate spin adjustment
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if (diff_nsecs == 0)
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/*
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* Throttles 6502 CPU down to the target CPU frequency (default is speed of original Apple //e).
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*
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* This uses an adaptive spin loop to stay closer to the target CPU frequency.
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*/
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void timing_throttle()
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{
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static float drift_interval=0.0;
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static int spinloop_adjust=0;
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uint8_t opcycles = cpu65__opcycles[cpu65_debug.opcode] + cpu65_debug.opcycles;
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uint8_t c=0;
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if (spinloop_adjust < 0)
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{
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// nothing to do
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c=-1;
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++spinloop_adjust;
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}
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else if (abs(diff_nsecs) > instruction_interval_nsecs)
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else if (spinloop_adjust > 0)
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{
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// spin for additional +/- X each instruction
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spinloop_count += diff_nsecs / instruction_interval_nsecs;
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spin_adjust_interval=INT_MAX;
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c=1;
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--spinloop_adjust;
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}
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else
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// spin for the desired/estimated number of nsecs
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_spin_loop(opcycles * (spinloop_count+c));
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drift_interval += opcycles*CYCLE_NSECS;
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if (drift_interval > CALIBRATE_INTERVAL)
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{
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// sub adjustment : spin for additional +/- 1 every interval
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spin_adjust_count = diff_nsecs < 0 ? -1 : 1;
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spin_adjust_interval = instruction_interval_nsecs / abs(diff_nsecs);
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// perform calibration
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spinloop_adjust = _calibrate_clock((long)drift_interval);
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drift_interval = 0.0;
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}
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}
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