new audio engine backend for native CoreAudio audio I/O, and PortMIDI for MIDI.

Code builds, runs and functions. Full code review still pending, and some possibly changes to organization of code within the backend is possible

libs/backends/wavesaudio/portmidi/src/porttime/ptmacosx_mach.c

@@ -0,0 +1,131 @@
+/* ptmacosx.c -- portable timer implementation for mac os x */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <CoreAudio/HostTime.h>
+
+#import <mach/mach.h>
+#import <mach/mach_error.h>
+#import <mach/mach_time.h>
+#import <mach/clock.h>
+#include <unistd.h>
+
+#include "porttime.h"
+#include "sys/time.h"
+#include "pthread.h"
+
+#define NSEC_PER_MSEC 1000000
+#define THREAD_IMPORTANCE 30
+
+static int time_started_flag = FALSE;
+static UInt64 start_time;
+static pthread_t pt_thread_pid;
+
+/* note that this is static data -- we only need one copy */
+typedef struct {
+    int id;
+    int resolution;
+    PtCallback *callback;
+    void *userData;
+} pt_callback_parameters;
+
+static int pt_callback_proc_id = 0;
+
+static void *Pt_CallbackProc(void *p)
+{
+    pt_callback_parameters *parameters = (pt_callback_parameters *) p;
+    int mytime = 1;
+
+    kern_return_t error;
+    thread_extended_policy_data_t extendedPolicy;
+    thread_precedence_policy_data_t precedencePolicy;
+
+    extendedPolicy.timeshare = 0;
+    error = thread_policy_set(mach_thread_self(), THREAD_EXTENDED_POLICY,
+                              (thread_policy_t)&extendedPolicy,
+                              THREAD_EXTENDED_POLICY_COUNT);
+    if (error != KERN_SUCCESS) {
+        mach_error("Couldn't set thread timeshare policy", error);
+    }
+
+    precedencePolicy.importance = THREAD_IMPORTANCE;
+    error = thread_policy_set(mach_thread_self(), THREAD_PRECEDENCE_POLICY,
+                              (thread_policy_t)&precedencePolicy,
+                              THREAD_PRECEDENCE_POLICY_COUNT);
+    if (error != KERN_SUCCESS) {
+        mach_error("Couldn't set thread precedence policy", error);
+    }
+    
+    
+    /* to kill a process, just increment the pt_callback_proc_id */
+    /* printf("pt_callback_proc_id %d, id %d\n", pt_callback_proc_id, parameters->id); */
+    while (pt_callback_proc_id == parameters->id) {
+        /* wait for a multiple of resolution ms */
+        UInt64 wait_time;
+        int delay = mytime++ * parameters->resolution - Pt_Time();
+	PtTimestamp timestamp;
+        if (delay < 0) delay = 0;
+        wait_time = AudioConvertNanosToHostTime((UInt64)delay * NSEC_PER_MSEC);
+        wait_time += AudioGetCurrentHostTime();
+        error = mach_wait_until(wait_time);
+	timestamp = Pt_Time();
+        (*(parameters->callback))(timestamp, parameters->userData);
+    }
+    free(parameters);
+    return NULL;
+}
+
+
+PtError Pt_Start(int resolution, PtCallback *callback, void *userData)
+{
+    if (time_started_flag) return ptAlreadyStarted;
+    start_time = AudioGetCurrentHostTime();
+    
+    if (callback) {
+        int res;
+        pt_callback_parameters *parms;
+
+        parms = (pt_callback_parameters *) malloc(sizeof(pt_callback_parameters));
+        if (!parms) return ptInsufficientMemory;
+        parms->id = pt_callback_proc_id;
+        parms->resolution = resolution;
+        parms->callback = callback;
+        parms->userData = userData;
+        res = pthread_create(&pt_thread_pid, NULL, Pt_CallbackProc, parms);
+        if (res != 0) return ptHostError;
+    }
+    
+    time_started_flag = TRUE;
+    return ptNoError;
+}
+
+
+PtError Pt_Stop()
+{
+    /* printf("Pt_Stop called\n"); */
+    pt_callback_proc_id++;
+    pthread_join(pt_thread_pid, NULL);
+    time_started_flag = FALSE;
+    return ptNoError;
+}
+
+
+int Pt_Started()
+{
+    return time_started_flag;
+}
+
+
+PtTimestamp Pt_Time()
+{
+    UInt64 clock_time, nsec_time;
+    clock_time = AudioGetCurrentHostTime() - start_time;
+    nsec_time = AudioConvertHostTimeToNanos(clock_time);
+    return (PtTimestamp)(nsec_time / NSEC_PER_MSEC);
+}
+
+
+void Pt_Sleep(int32_t duration)
+{
+    usleep(duration * 1000);
+}