From 8b71d0ebf934f5029a29aa89ba2b49ee4c5954cc Mon Sep 17 00:00:00 2001
From: notaz <notasas@gmail.com>
Date: Sun, 11 Mar 2007 23:46:51 +0000
Subject: [PATCH] buffering

git-svn-id: file:///home/notaz/opt/svn/PicoDrive@67 be3aeb3a-fb24-0410-a615-afba39da0efa
---
 Pico/cd/buffering.c | 112 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)
 create mode 100644 Pico/cd/buffering.c

diff --git a/Pico/cd/buffering.c b/Pico/cd/buffering.c
new file mode 100644
index 0000000..5afc6e8
--- /dev/null
+++ b/Pico/cd/buffering.c
@@ -0,0 +1,112 @@
+#include "../PicoInt.h"
+
+//#include <stdlib.h>
+
+int PicoCDBuffers = 0;
+static unsigned char *cd_buffer = NULL;
+static int prev_lba = 0x80000000;
+
+static int hits, reads;
+
+
+void PicoCDBufferInit(void)
+{
+	void *tmp;
+
+	prev_lba = 0x80000000;
+	hits = reads = 0;
+
+	if (PicoCDBuffers <= 1) {
+		PicoCDBuffers = 0;
+		return; /* buffering off */
+	}
+
+	/* try alloc'ing until we succeed */
+	while (PicoCDBuffers > 0)
+	{
+		tmp = realloc(cd_buffer, PicoCDBuffers * 2048);
+		if (tmp != NULL) break;
+		PicoCDBuffers >>= 1;
+	}
+
+	if (PicoCDBuffers <= 0) return; /* buffering became off */
+
+	cd_buffer = tmp;
+}
+
+
+void PicoCDBufferFree(void)
+{
+	if (cd_buffer) {
+		free(cd_buffer);
+		cd_buffer = NULL;
+	}
+	if (reads)
+		printf("CD buffer hits: %i/%i (%i%%)\n", hits, reads, hits * 100 / reads);
+}
+
+
+/* this is a try to fight slow SD access of GP2X */
+void PicoCDBufferRead(void *dest, int lba)
+{
+	int is_bin, offs, read_len;
+	reads++;
+
+	is_bin = Pico_mcd->TOC.Tracks[0].ftype == TYPE_BIN;
+
+	if (PicoCDBuffers <= 0)
+	{
+		/* no buffering */
+		int where_seek = is_bin ? (lba * 2352 + 16) : (lba << 11);
+		pm_seek(Pico_mcd->TOC.Tracks[0].F, where_seek, SEEK_SET);
+		pm_read(dest, 2048, Pico_mcd->TOC.Tracks[0].F);
+		return;
+	}
+
+	/* hit? */
+	offs = lba - prev_lba;
+	if (offs >= 0 && offs < PicoCDBuffers)
+	{
+		hits++;
+		if (offs == 0) dprintf("CD buffer seek to old %i -> %i\n", prev_lba, lba);
+		memcpy32(dest, (int *)(cd_buffer + offs*2048), 2048/4);
+		return;
+	}
+
+	if (prev_lba + PicoCDBuffers != lba)
+	{
+		int where_seek = is_bin ? (lba * 2352 + 16) : (lba << 11);
+		dprintf("CD buffer seek %i -> %i\n", prev_lba, lba);
+		pm_seek(Pico_mcd->TOC.Tracks[0].F, where_seek, SEEK_SET);
+	}
+
+	dprintf("CD buffer miss %i -> %i\n", prev_lba, lba);
+
+	if (lba < prev_lba && prev_lba - lba < PicoCDBuffers)
+	{
+		dprintf("CD buffer move");
+		read_len = prev_lba - lba;
+		memmove(cd_buffer + read_len*2048, cd_buffer, (PicoCDBuffers - read_len)*2048);
+	}
+	else
+	{
+		read_len = PicoCDBuffers;
+	}
+
+	if (is_bin)
+	{
+		int i;
+		for (i = 0; i < read_len; i++)
+		{
+			pm_read(cd_buffer + i*2048, 2048, Pico_mcd->TOC.Tracks[0].F);
+			pm_seek(Pico_mcd->TOC.Tracks[0].F, 304, SEEK_CUR);
+		}
+	}
+	else
+	{
+		pm_read(cd_buffer, read_len*2048, Pico_mcd->TOC.Tracks[0].F);
+	}
+	memcpy32(dest, (int *) cd_buffer, 2048/4);
+	prev_lba = lba;
+}
+
-- 
2.39.2