From 9d7f739e34cfaa284f8bdd1f36bf6e8d7b9d9cef Mon Sep 17 00:00:00 2001
From: Zakk <zakk@rsdio.com>
Date: Tue, 12 Mar 2024 19:53:45 -0400
Subject: [PATCH] PSX: match user_io buffer size to chd hunk size

---
 support/psx/psx.cpp | 9 +++++++++
 support/psx/psx.h   | 1 +
 user_io.cpp         | 7 +++++++
 3 files changed, 17 insertions(+)

diff --git a/support/psx/psx.cpp b/support/psx/psx.cpp
index baefd9e..34cbf36 100644
--- a/support/psx/psx.cpp
+++ b/support/psx/psx.cpp
@@ -467,6 +467,15 @@ void psx_fill_blanksave(uint8_t *buffer, uint32_t lba, int cnt)
 static toc_t toc = {};
 #define CD_SECTOR_LEN 2352
 
+int psx_chd_hunksize()
+{
+	if (toc.chd_f)
+		return toc.chd_hunksize;
+
+	return 0;
+}
+
+
 void psx_read_cd(uint8_t *buffer, int lba, int cnt)
 {
 	//printf("req lba=%d, cnt=%d\n", lba, cnt);
diff --git a/support/psx/psx.h b/support/psx/psx.h
index 749d325..2ea5445 100644
--- a/support/psx/psx.h
+++ b/support/psx/psx.h
@@ -4,6 +4,7 @@
 void psx_mount_cd(int f_index, int s_index, const char *filename);
 void psx_fill_blanksave(uint8_t *buffer, uint32_t lba, int cnt);
 void psx_read_cd(uint8_t *buffer, int lba, int cnt);
+int psx_chd_hunksize();
 const char* psx_get_game_id();
 void psx_poll();
 
diff --git a/user_io.cpp b/user_io.cpp
index 4c7d20c..3cca5d6 100644
--- a/user_io.cpp
+++ b/user_io.cpp
@@ -3118,6 +3118,13 @@ void user_io_poll()
 			else if (op & 1)
 			{
 				uint32_t buf_n = sizeof(buffer[0]) / blksz;
+				int psx_blksz = 0;
+				if (is_psx() && blksz == 2352)
+				{
+					//returns 0 if the mounted disk is not a chd, otherwise returns the chd hunksize in bytes
+					psx_blksz = psx_chd_hunksize();
+					if (psx_blksz && psx_blksz <= sizeof(buffer[0])) buf_n = psx_blksz / blksz;
+				}
 				//printf("SD RD (%llu,%d) on %d, WIDE=%d\n", lba, blksz, disk, fio_size);
 
 				int done = 0;