From 549a8544a0a2b7507c7022d43c363d0746a71a74 Mon Sep 17 00:00:00 2001
From: OBattler <oubattler@gmail.com>
Date: Sat, 16 Jul 2022 04:29:19 +0200
Subject: [PATCH] Rewrote the NVR periodic timer for better performance.

---
 src/nvr_at.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/src/nvr_at.c b/src/nvr_at.c
index b164d948d..2bf8be383 100644
--- a/src/nvr_at.c
+++ b/src/nvr_at.c
@@ -496,6 +496,8 @@ timer_load_count(nvr_t *nvr)
     int c = nvr->regs[RTC_REGA] & REGA_RS;
     local_t *local = (local_t *) nvr->data;
 
+    timer_disable(&local->rtc_timer);
+
     if ((nvr->regs[RTC_REGA] & 0x70) != 0x20) {
 	local->state = 0;
 	return;
@@ -509,9 +511,11 @@ timer_load_count(nvr_t *nvr)
 		break;
 	case 1: case 2:
 		local->count = 1 << (c + 6);
+		timer_set_delay_u64(&local->rtc_timer, (local->count) * RTCCONST);
 		break;
 	default:
 		local->count = 1 << (c - 1);
+		timer_set_delay_u64(&local->rtc_timer, (local->count) * RTCCONST);
 		break;
     }
 }
@@ -523,20 +527,16 @@ timer_intr(void *priv)
     nvr_t *nvr = (nvr_t *)priv;
     local_t *local = (local_t *)nvr->data;
 
-    timer_advance_u64(&local->rtc_timer, RTCCONST);
-
     if (local->state == 1) {
-	if (--local->count == 0) {
-		timer_load_count(nvr);
+	timer_load_count(nvr);
 
-		nvr->regs[RTC_REGC] |= REGC_PF;
-		if (nvr->regs[RTC_REGB] & REGB_PIE) {
-			nvr->regs[RTC_REGC] |= REGC_IRQF;
+	nvr->regs[RTC_REGC] |= REGC_PF;
+	if (nvr->regs[RTC_REGB] & REGB_PIE) {
+		nvr->regs[RTC_REGC] |= REGC_IRQF;
 
-			/* Generate an interrupt. */
-			if (nvr->irq != -1)
-				picint(1 << nvr->irq);
-		}
+		/* Generate an interrupt. */
+		if (nvr->irq != -1)
+			picint(1 << nvr->irq);
 	}
     }
 }
@@ -809,6 +809,7 @@ nvr_read(uint16_t addr, void *priv)
     return(ret);
 }
 
+
 /* Secondary NVR write - used by SMC. */
 static void
 nvr_sec_write(uint16_t addr, uint8_t val, void *priv)
@@ -824,6 +825,7 @@ nvr_sec_read(uint16_t addr, void *priv)
     return nvr_read(0x72 + (addr & 1), priv);
 }
 
+
 /* Reset the RTC state to 1980/01/01 00:00. */
 static void
 nvr_reset(nvr_t *nvr)
@@ -883,8 +885,7 @@ nvr_at_speed_changed(void *priv)
     nvr_t *nvr = (nvr_t *) priv;
     local_t *local = (local_t *) nvr->data;
 
-    timer_disable(&local->rtc_timer);
-    timer_set_delay_u64(&local->rtc_timer, RTCCONST);
+    timer_load_count(nvr);
 
     timer_disable(&local->update_timer);
     if (local->ecount > 0ULL)
@@ -1081,7 +1082,6 @@ nvr_at_init(const device_t *info)
 		nvr->regs[RTC_REGA] = (nvr->regs[RTC_REGA] & 0x8f) | 0x20;
 	nvr_at_reset(nvr);
 	timer_load_count(nvr);
-	timer_set_delay_u64(&local->rtc_timer, RTCCONST);
 
 	/* Set up the I/O handler for this device. */
 	io_sethandler(0x0070, 2,