first cut at auto fast-loading of disk images

- automatically adjusts cpu timing to fastest if drive motor accessed recently and no audio/video
    - TODO: audio output clipping issue when (un)pausing audio outpu

src/display.c

@@ -53,6 +53,8 @@ static uint8_t video__int_font[3][0x4000];
 int video__current_page; // current visual page
 int video__strictcolors = 1;// refactor : should be static
 
+extern volatile bool _vid_dirty;
+
 // Video constants -- sourced from AppleWin
 static const bool bVideoScannerNTSC = true;
 static const int kHBurstClock   =    53; // clock when Color Burst starts
@@ -571,6 +573,7 @@ static inline void _plot_lores(uint8_t **d, const uint32_t val) {
 
 #ifdef INTERFACE_CLASSIC
 void video_plotchar( int x, int y, int scheme, uint8_t c ) {
+    _vid_dirty = true;
     uint8_t *d;
     uint8_t *s;
 
@@ -653,11 +656,13 @@ static inline void _plot_character(const unsigned int font_off, uint8_t *fb_ptr)
 
 static inline void _plot_character0(uint16_t ea, uint8_t b)
 {
+    _vid_dirty = (video__current_page == 0);
     _plot_character(b<<7/* *128 */, video__fb1+video__screen_addresses[ea-0x0400]);
 }
 
 static inline void _plot_character1(uint16_t ea, uint8_t b)
 {
+    _vid_dirty = (video__current_page == 1);
     _plot_character(b<<7/* *128 */, video__fb2+video__screen_addresses[ea-0x0800]);
 }
 
@@ -676,6 +681,7 @@ static inline void _plot_80character(const unsigned int font_off, uint8_t *fb_pt
 // FIXME TODO NOTE : dup'ing work here?
 static inline void _plot_80character0(uint16_t ea, uint8_t b)
 {
+    _vid_dirty = (video__current_page == 0);
     b = apple_ii_64k[1][ea];
     _plot_80character(b<<6/* *64 */, video__fb1+video__screen_addresses[ea-0x0400]);
     b = apple_ii_64k[0][ea];
@@ -684,6 +690,7 @@ static inline void _plot_80character0(uint16_t ea, uint8_t b)
 
 static inline void _plot_80character1(uint16_t ea, uint8_t b)
 {
+    _vid_dirty = (video__current_page == 1);
     b = apple_ii_64k[1][ea];
     _plot_80character(b<<6/* *64 */, video__fb2+video__screen_addresses[ea-0x0800]);
     b = apple_ii_64k[0][ea];
@@ -718,11 +725,13 @@ static inline void _plot_block(const uint32_t val, uint8_t *fb_ptr) {
 /* plot lores block first page */
 static inline void _plot_block0(uint16_t ea, uint8_t b)
 {
+    _vid_dirty = (video__current_page == 0);
     _plot_block(b, video__fb1+video__screen_addresses[ea-0x0400]);
 }
 
 static inline void _plot_block1(uint16_t ea, uint8_t b)
 {
+    _vid_dirty = (video__current_page == 1);
     _plot_block(b, video__fb2+video__screen_addresses[ea-0x0800]);
 }
 
@@ -803,6 +812,7 @@ static inline void _plot_dhires_pixels(uint8_t idx, uint8_t *fb_ptr) {
 
 // PlotDHires
 static inline void _plot_dhires(uint16_t base, uint16_t ea, uint8_t *fb_base) {
+    _vid_dirty = true;
     ea &= ~0x1;
 
     uint16_t memoff = ea - base;
@@ -927,6 +937,7 @@ static inline void _plot_hires_pixels(uint8_t *dst, const uint8_t *src) {
 
 // PlotByte
 static inline void _plot_hires(uint16_t ea, uint8_t b, bool is_even, uint8_t *fb_ptr) {
+
     uint8_t _buf[DYNAMIC_SZ] = { 0 };
     uint8_t *color_buf = (uint8_t *)_buf; // <--- work around for -Wstrict-aliasing
     uint8_t *apple2_vmem = (uint8_t *)apple_ii_64k[0];
@@ -1025,8 +1036,10 @@ static inline void _draw_hires_graphics(uint16_t ea, uint8_t b, bool is_even, ui
     uint8_t *fb_base = NULL;
     if (page) {
         off -= 0x2000;
+        _vid_dirty = (video__current_page == 1);
         fb_base = video__fb2;
     } else {
+        _vid_dirty = (video__current_page == 0);
         fb_base = video__fb1;
     }
     _plot_hires(ea, b, is_even, fb_base+video__screen_addresses[off]);
@@ -1080,6 +1093,10 @@ GLUE_C_WRITE(video__write_2e_odd1_mixed)
     _draw_hires_graphics(ea, b, /*even*/false, 1, (SS_TEXT|SS_MIXED));
 }
 
+bool video_dirty(void) {
+    return _vid_dirty;
+}
+
 void video_redraw(void) {
 
     // temporarily reset softswitches

src/timing.c

@@ -47,6 +47,7 @@ static bool alt_speed_enabled = false;
 
 double cpu_scale_factor = 1.0;
 double cpu_altscale_factor = 1.0;
+bool auto_adjust_speed = true;
 
 int gc_cycles_timer_0 = 0;
 int gc_cycles_timer_1 = 0;
@@ -54,7 +55,7 @@ int gc_cycles_timer_1 = 0;
 volatile uint8_t emul_reinitialize = 0;
 pthread_t cpu_thread_id = 0;
 
-static unsigned int g_nCyclesExecuted; // # of cycles executed up to last IO access
+static unsigned int g_nCyclesExecuted = 0; // # of cycles executed up to last IO access
 
 // -----------------------------------------------------------------------------
 
@@ -245,21 +246,24 @@ void *cpu_thread(void *dummyptr) {
 #if DEBUG_TIMING
             dbg_cycles_executed += cpu65_cycle_count;
 #endif
-#ifdef AUDIO_ENABLED
             unsigned int uActualCyclesExecuted = cpu65_cycle_count;
             g_dwCyclesThisFrame += uActualCyclesExecuted;
 
+#ifdef AUDIO_ENABLED
             MB_UpdateCycles(uActualCyclesExecuted);   // Update 6522s (NB. Do this before updating g_nCumulativeCycles below)
+#endif
 
             // N.B.: IO calls that depend on accurate timing will update g_nCyclesExecuted
-            const unsigned int nRemainingCycles = uActualCyclesExecuted - g_nCyclesExecuted;
+            const int nRemainingCycles = uActualCyclesExecuted - g_nCyclesExecuted;
+            assert(nRemainingCycles >= 0);
             g_nCumulativeCycles += nRemainingCycles;
 
             if (!g_bFullSpeed)
             {
+#ifdef AUDIO_ENABLED
                 SpkrUpdate(uActualCyclesExecuted); // play audio
-            }
 #endif
+            }
 
             if (g_dwCyclesThisFrame >= dwClksPerFrame)
             {
@@ -274,6 +278,28 @@ void *cpu_thread(void *dummyptr) {
             pthread_mutex_unlock(&interface_mutex);
             // -UNLOCK--------------------------------------------------------------------------------------- SAMPLE tj
 
+            if (auto_adjust_speed) {
+                deltat = timespec_diff(disk6.motor_time, tj, &negative);
+                assert(!negative);
+                if (!g_bFullSpeed &&
+#ifdef AUDIO_ENABLED
+                        !Spkr_IsActive() &&
+#endif
+                        !video_dirty() && (!disk6.motor_off && (deltat.tv_sec || deltat.tv_nsec > DISK_MOTOR_QUIET_NSECS)) )
+                {
+                    TIMING_LOG("auto switching to full speed");
+                    _switch_to_fullspeed();
+                } else if (g_bFullSpeed && (
+#ifdef AUDIO_ENABLED
+                            Spkr_IsActive() ||
+#endif
+                            video_dirty() || (disk6.motor_off && (deltat.tv_sec || deltat.tv_nsec > DISK_MOTOR_QUIET_NSECS))) )
+                {
+                    TIMING_LOG("auto switching to regular speed");
+                    _switch_to_regular_speed(alt_speed_enabled ? cpu_altscale_factor : cpu_scale_factor);
+                }
+            }
+
             if (!g_bFullSpeed) {
                 deltat = timespec_diff(ti, tj, &negative);
                 assert(!negative);

src/timing.h

@@ -45,6 +45,7 @@ extern int g_nCpuCyclesFeedback;
 
 extern double cpu_scale_factor;
 extern double cpu_altscale_factor;
+extern bool auto_adjust_speed;
 
 extern pthread_t cpu_thread_id;
 

src/video/glvideo.c

@@ -34,6 +34,8 @@ enum {
 
 bool safe_to_do_opengl_logging = false;
 
+volatile bool _vid_dirty = true;
+
 static int windowWidth = SCANWIDTH*1.5;
 static int windowHeight = SCANHEIGHT*1.5;
 
@@ -649,6 +651,8 @@ static void gldriver_render(void) {
     // Draw the CRT object
     glDrawElements(GL_TRIANGLES, crtNumElements, crtElementType, 0);
 
+    _vid_dirty = false;
+
 #if USE_GLUT
     glutSwapBuffers();
 #endif

src/video/video.h

@@ -116,6 +116,11 @@ void video_plotchar(int row, int col, int color, uint8_t code);
  */
 const uint8_t * const video_current_framebuffer();
 
+/*
+ * True if anything changed in framebuffer and not yet drawn
+ */
+bool video_dirty(void);
+
 /*
  * VBL routines
  */