Fix the game controller routines to use proper timers

* Add proper timers according to spec mentioned in _Understanding the Apple IIe_
    * This will allow us to refactor/eliminate all the hackish joystick adjustment routines

src/cpu.S

@@ -2693,6 +2693,8 @@ continue:
                 movb    SN(cpu65__opcycles)(,%eax,1), %al
                 addb    DebugCycleCount, %al
                 addw    %ax, SN(cpu65_cycle_count)          // TODO: cycle counting is slightly incorrect, it should be done earlier per instruction ...
+                subl    %eax, SN(gc_cycles_timer_0)
+                subl    %eax, SN(gc_cycles_timer_1)
                 subw    %ax, SN(cpu65_cycles_to_execute)    //       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ orly?
                 jle     exit_cpu65_run
                 xorl    %eax, %eax

src/memory.S

@@ -352,9 +352,6 @@ iie_hires_on_80store_off:
 
 /*****************************************************************************/
 
-.comm		joy_trigger0, 2
-.comm		joy_trigger1, 2
-
 E(read_button0)
 		movb	SN(joy_button0), %al
 		ret
@@ -367,40 +364,6 @@ E(read_button2)
 		movb	SN(joy_button2), %al
 		ret
 
-E(read_gc0)
-		cmpw	$0xFF, joy_trigger0
-		jle	read_gc0_cont
-read_gc0_lo:
-                movb    $0, %al
-                ret
-read_gc0_cont:
-                incw    joy_trigger0
-		movw	joy_trigger0, %ax
-		cmpw	%ax, SN(joy_x)
-		jl	read_gc0_reset
-		movb	$0xFF, %al
-		ret
-read_gc0_reset:
-                movw    $0xFF, joy_trigger0
-                jmp     read_gc0_lo
-
-E(read_gc1)
-		cmpw	$0xFF, joy_trigger1
-		jle	read_gc1_cont
-read_gc1_lo:
-		movb	$0, %al
-		ret
-read_gc1_cont:
-                incw    joy_trigger1
-		movw	joy_trigger1, %ax
-		cmpw	%ax, SN(joy_y)
-		jl	read_gc1_reset
-		movb	$0xFF, %al
-		ret
-read_gc1_reset:
-                movw    $0xFF, joy_trigger0
-                jmp     read_gc1_lo
-
 /* NOTE : Game Controller axis 2 & 3 is not hooked up on a normal //e */
 E(iie_read_gc2)
                 movb    $0, %al
@@ -410,11 +373,6 @@ E(iie_read_gc3)
                 movb    $0, %al
 		ret
 
-E(read_gc_strobe)
-		movw	$0, joy_trigger0
-		movw	$0, joy_trigger1
-		ret
-
 E(iie_c080)
 		testl	$SS_ALTZP, SN(softswitches)
 		jz	lc_c080

src/misc.c

@@ -762,6 +762,50 @@ static void c_initialize_firsttime()
     reinitialize();
 }
 
+// Read Game Controller (paddle) strobe ...
+// From _Understanding the Apple IIe_ :
+//  * 7-29, discussing PREAD : "The timer duration will vary between 2 and 3302 usecs"
+//  * 7-30, timer reset : "But the timer pulse may still be high from the previous [strobe access] and the timers are
+//  not retriggered by C07X' if they have not yet reset from the previous trigger"
+#define JOY_STEP_USEC (3300.0 / 256.0)
+#define CYCLES_PER_USEC (CLK_6502 / 1000000)
+#define JOY_STEP_CYCLES (JOY_STEP_USEC / CYCLES_PER_USEC)
+extern short joy_x;
+extern short joy_y;
+GLUE_C_READ(read_gc_strobe)
+{
+    if (gc_cycles_timer_0 <= 0)
+    {
+        gc_cycles_timer_0 = (int)(joy_x * JOY_STEP_CYCLES) + 2;
+    }
+    if (gc_cycles_timer_1 <= 0)
+    {
+        gc_cycles_timer_1 = (int)(joy_y * JOY_STEP_CYCLES) + 2;
+    }
+    // NOTE: unimplemented GC2 and GC3 timers since they were not wired on the //e ...
+    return 0;
+}
+
+GLUE_C_READ(read_gc0)
+{
+    if (gc_cycles_timer_0 <= 0)
+    {
+        gc_cycles_timer_0 = 0;
+        return 0;
+    }
+    return 0xFF;
+}
+
+GLUE_C_READ(read_gc1)
+{
+    if (gc_cycles_timer_1 <= 0)
+    {
+        gc_cycles_timer_1 = 0;
+        return 0;
+    }
+    return 0xFF;
+}
+
 // HACK FIXME TODO : candidate for GLUE_C_READ(...)
 void c_read_random() {
     static unsigned int seed=0;

src/timing.c

@@ -34,6 +34,9 @@ static bool alt_speed_enabled = false;
 double cpu_scale_factor = 1.0;
 double cpu_altscale_factor = 1.0;
 
+int gc_cycles_timer_0 = 0;
+int gc_cycles_timer_1 = 0;
+
 uint8_t emul_reinitialize;
 
 static unsigned int g_nCyclesExecuted; // # of cycles executed up to last IO access

src/timing.h

@@ -45,6 +45,9 @@ extern int g_nCpuCyclesFeedback;
 extern double cpu_scale_factor;
 extern double cpu_altscale_factor;
 
+extern int gc_cycles_timer_0;
+extern int gc_cycles_timer_1;
+
 struct timespec timespec_diff(struct timespec start, struct timespec end, bool *negative);
 
 void timing_toggle_cpu_speed();