From 96b3fa92751ff06b21c1197cd969fa453b93509e Mon Sep 17 00:00:00 2001
From: Sorgelig <pour.garbage@gmail.com>
Date: Sun, 6 Feb 2022 23:02:12 +0800
Subject: [PATCH] PSX: add encryption map generation (markun).

---
 support/psx/psx.cpp | 60 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)

diff --git a/support/psx/psx.cpp b/support/psx/psx.cpp
index 5b2dc22..459af85 100644
--- a/support/psx/psx.cpp
+++ b/support/psx/psx.cpp
@@ -110,6 +110,57 @@ static int get_bin(const char *cue)
 	return res;
 }
 
+static uint32_t libCryptSectors[16] =
+{
+	14105,
+	14231,
+	14485,
+	14579,
+	14649,
+	14899,
+	15056,
+	15130,
+	15242,
+	15312,
+	15378,
+	15628,
+	15919,
+	16031,
+	16101,
+	16167,
+};
+
+static uint32_t msfToLba(uint32_t m, uint32_t s, uint32_t f)
+{
+	return (m * 60 + s) * 75 + f;
+}
+
+static uint8_t bcdToDec(uint8_t bcd)
+{
+	return (bcd >> 4) * 10 + (bcd & 0x0F);
+}
+
+#define SBI_HEADER_SIZE 4
+#define SBI_BLOCK_SIZE  14
+
+static uint16_t libCryptMask(const char *sbifile)
+{
+	int sz;
+	uint16_t mask = 0;
+	if ((sz = FileLoad(sbifile, buf, sizeof(buf))))
+	{
+		for (int i = 0;; i++)
+		{
+			int pos = SBI_HEADER_SIZE + i * SBI_BLOCK_SIZE;
+			if (pos >= sz) break;
+			uint32_t lba = msfToLba(bcdToDec(buf[pos]), bcdToDec(buf[pos + 1]), bcdToDec(buf[pos + 2]));
+			for (int m = 0; m < 16; m++) if (libCryptSectors[m] == lba) mask |= (1 << (15 - m));
+		}
+	}
+
+	return mask;
+}
+
 void psx_mount_cd(int f_index, int s_index, const char *filename)
 {
 	static char last_dir[1024] = {};
@@ -154,6 +205,15 @@ void psx_mount_cd(int f_index, int s_index, const char *filename)
 
 	if (loaded)
 	{
+		strcpy(buf, filename);
+		strcpy((name_len > 4) ? buf + name_len - 4 : buf + name_len, ".sbi");
+
+		uint16_t mask = libCryptMask(buf);
+		user_io_set_index(250);
+		user_io_set_download(1);
+		user_io_file_tx_data((const uint8_t*)&mask, 2);
+		user_io_set_download(0);
+
 		user_io_set_index(f_index);
 		process_ss(filename, name_len != 0);