From 19b3e04b05684dfd11c153c896072ca19f675b9f Mon Sep 17 00:00:00 2001
From: David Shadoff <46657586+dshadoff@users.noreply.github.com>
Date: Mon, 11 May 2020 03:38:23 -0400
Subject: [PATCH] pcecd: minor timing adjustments

Minor timing adjustments
---
 support/pcecd/pcecd.cpp    | 10 ++++++++--
 support/pcecd/pcecdd.cpp   |  8 +++++++-
 support/pcecd/seektime.cpp | 12 ++++++------
 3 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/support/pcecd/pcecd.cpp b/support/pcecd/pcecd.cpp
index 476a943..08ad2ef 100644
--- a/support/pcecd/pcecd.cpp
+++ b/support/pcecd/pcecd.cpp
@@ -24,8 +24,14 @@ void pcecd_poll()
 
 	if (CheckTimer(poll_timer))
 	{
-		poll_timer += 13 + (!adj ? 1 : 0);
-		if (++adj >= 3) adj = 0;
+		if ((!pcecdd.latency) && (pcecdd.state == PCECD_STATE_READ)) {
+			poll_timer += 16 + ((adj == 10) ? 1 : 0);	// 16.1ms between frames if reading data */
+			if (--adj <= 0) adj = 10;
+		} else {
+			poll_timer += 13 + ((adj == 3) ? 1 : 0);	// 13.33ms otherwise (including latency counts) */
+			if (adj > 3) adj = 3;
+			if (--adj <= 0) adj = 3;
+		}
 
 		if (pcecdd.has_status && !pcecdd.latency) {
 			uint16_t s;
diff --git a/support/pcecd/pcecdd.cpp b/support/pcecd/pcecdd.cpp
index ad4c3f4..59fba26 100644
--- a/support/pcecd/pcecdd.cpp
+++ b/support/pcecd/pcecdd.cpp
@@ -538,7 +538,13 @@ void pcecdd_t::CommandExec() {
 			new_lba = this->toc.tracks[index].start;
 		}*/
 
-		this->latency = (int)(get_cd_seek_ms(this->lba, new_lba)/13.33);
+		/* HuVideo streams by fetching 120 sectors at a time, taking advantage of the geometry
+		 * of the disc to reduce/eliminate seek time */
+		if ((this->lba == new_lba) && (cnt_ == 120)) {
+			this->latency = 0;
+		} else {
+			this->latency = (int)(get_cd_seek_ms(this->lba, new_lba)/13.33);
+		}
 		printf("seek time ticks: %d\n", this->latency);
 
 		this->lba = new_lba;
diff --git a/support/pcecd/seektime.cpp b/support/pcecd/seektime.cpp
index 0211c8f..adfe96d 100644
--- a/support/pcecd/seektime.cpp
+++ b/support/pcecd/seektime.cpp
@@ -93,27 +93,27 @@ float get_cd_seek_ms(int start_sector, int target_sector)
 	// Now, we use the algorithm to determine how long to wait
 	if (abs(target_sector - start_sector) < 2)
 	{
-		milliseconds = (3 * 1000 / 60);
+		milliseconds = (2 * 1000 / 60);
 	}
 	else if (abs(target_sector - start_sector) < 5)
 	{
-		milliseconds = (9 * 1000 / 60) + (float)(sector_list[target_index].rotation_ms * 0.7);
+		milliseconds = (9 * 1000 / 60) + (float)(sector_list[target_index].rotation_ms * 0.75);
 	}
 	else if (track_difference <= 80)
 	{
-		milliseconds = (16 * 1000 / 60) + (float)(sector_list[target_index].rotation_ms * 0.7);
+		milliseconds = (17 * 1000 / 60) + (float)(sector_list[target_index].rotation_ms * 0.75);
 	}
 	else if (track_difference <= 160)
 	{
-		milliseconds = (22 * 1000 / 60) + (float)(sector_list[target_index].rotation_ms * 0.7);
+		milliseconds = (22 * 1000 / 60) + (float)(sector_list[target_index].rotation_ms * 0.75);
 	}
 	else if (track_difference <= 644)
 	{
-		milliseconds = (22 * 1000 / 60) + (float)(sector_list[target_index].rotation_ms * 0.7) + (float)((track_difference - 161) * 16.66 / 80);
+		milliseconds = (22 * 1000 / 60) + (float)(sector_list[target_index].rotation_ms * 0.75) + (float)((track_difference - 161) * 16.66 / 80);
 	}
 	else
 	{
-		milliseconds = (36 * 1000 / 60) + (float)((track_difference - 644) * 16.66 / 195);
+		milliseconds = (36 * 1000 / 60) + (float)(sector_list[target_index].rotation_ms * 0.5) + (float)((track_difference - 644) * 16.66 / 195);
 	}
 
 	printf("From sector %d to sector %d:\n", start_sector, target_sector);