Fix counter scheduling when target equals max value

When target is 0xFFFF, the CountToTarget and CountToOverflow events
coincide at the same counter value. Skip the redundant target phase
and schedule CountToOverflow directly, so the overflow flag is visible
on the first mode register read without requiring two update() calls.

Restore small target values for tests that only check flag presence,
keeping the larger target only for the back-to-back read test.

Signed-off-by: Nicolas 'Pixel' Noble <nicolas@nobis-crew.org>

Author: nicolasnoble

src/core/psxcounters.cc

@@ -48,7 +48,13 @@ inline void PCSX::Counters::writeCounterInternal(uint32_t index, uint32_t value)
     // The comparison boundary needs more precise measurement to determine if
     // reset happens on the same cycle as reaching target or the next cycle.
     // TODO: determine exact reset timing with cycle-accurate measurement.
-    if (value < m_rcnts[index].target) {
+    // Schedule next event: target hit first (for flag/IRQ), then overflow.
+    // If RcCountToTarget is not set, the counter doesn't reset at target,
+    // but bit 11 (RcCountEqTarget) is still set when the counter passes
+    // the target value. However, if target == 0xFFFF, the target and
+    // overflow events coincide - skip straight to overflow to avoid
+    // redundant processing.
+    if (value < m_rcnts[index].target && m_rcnts[index].target != 0xffff) {
         m_rcnts[index].cycle = m_rcnts[index].target * m_rcnts[index].rate;
         m_rcnts[index].counterState = CountToTarget;
     } else {

src/mips/tests/timers/timers.c

@@ -159,15 +159,15 @@ CESTER_TEST(timerModeWriteResetsCounter, timer_tests,
  * ================================================================= */
 CESTER_TEST(timerHitTargetFlagSetAndCleared, timer_tests,
     /* Warmup pass to prime icache */
-    COUNTERS[2].target = 0x0010;
+    COUNTERS[2].target = 0x1000;
     COUNTERS[2].mode = TM_RESET_TARGET;
-    BUSY_WAIT(500);
+    BUSY_WAIT(50000);
     (void)COUNTERS[2].mode;
     (void)COUNTERS[2].mode;
 
     /* Real measurement */
     COUNTERS[2].mode = TM_RESET_TARGET;
-    BUSY_WAIT(500);
+    BUSY_WAIT(50000);
 
     uint16_t mode1 = COUNTERS[2].mode;
     uint16_t mode2 = COUNTERS[2].mode;