From: Alan Cox <alan@linux.intel.com>
Date: Thu, 19 Feb 2015 23:15:13 +0000 (+0000)
Subject: bank16k_low: first cut at swap
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=11ee533986edc1f5ffd25366c5ee500bbac7b5cd;p=FUZIX.git

bank16k_low: first cut at swap

There are a couple of 6502 crawly horrors around the stack left to resolve!
---

diff --git a/Kernel/bank16k_low.c b/Kernel/bank16k_low.c
index 0b16ac0c..adcaedd2 100644
--- a/Kernel/bank16k_low.c
+++ b/Kernel/bank16k_low.c
@@ -25,6 +25,11 @@
 
 
 #ifdef CONFIG_BANK16_LOW
+
+#ifndef CONFIG_LOW_PAGE
+#define SWAP_SIZE_EXCL_ZP	SWAP_SIZE
+#endif
+
 /*
  * Map handling: We have flexible paging. Each map table consists of a set of pages
  * with the last page repeated to fill any holes.
@@ -150,4 +155,109 @@ uint16_t pagemap_mem_used(void)
 	return pfptr << 4;
 }
 
+
+#ifdef SWAPDEV
+
+/*
+ *	Swap out the memory of a process to make room
+ *	for something else. For bank16k do this as four operations
+ *	ready for when we pass page values not processes to the drivers
+ *
+ *	FIXME: We also need to swap out page 0/1 on 6502 (ZP and S) as well
+ *	as looking at the best way to include the uarea in the swaps
+ */
+
+int swapout(ptptr p)
+{
+	uint16_t page = p->p_page;
+	uint16_t blk;
+	uint16_t map;
+	uint16_t base = SWAPBASE;
+	uint16_t size = (0x4000 - SWAPBASE) >> 9;
+
+	swapproc = p;
+
+	if (page)
+		panic("%x: process already swapped!\n", p);
+#ifdef DEBUG
+	kprintf("Swapping out %x (%d)\n", p, p->p_page);
+#endif
+
+	/* Are we out of swap ? */
+	map = swapmap_alloc();
+	if (map == 0)
+		return ENOMEM;
+	blk = map * SWAP_SIZE;
+
+#ifdef CONFIG_HAS_LOW_PAGE
+	swapwrite(SWAPDEV, blk, 1, 0x0000);
+	blk++;
+#endif
+
+	/* Write the app (and possibly the uarea etc..) to disk */
+	for (i = 0; i < 4; i ++) {
+		swapwrite(SWAPDEV, blk, size, base);
+		base += 0x4000;
+		/* Last bank is determined by SWAP SIZE. We do the maths
+		   in 512's (0x60 = 0xC000) */
+		if (i == 3)
+			size = SWAP_SIZE_EXCL_ZP - 0x60;
+		else
+			size = 0x20;
+	}
+	pagemap_free(p);
+	p->p_page = 0;
+	p->p_page2 = map;
+
+#ifdef DEBUG
+	kprintf("%x: swapout done %d\n", p, p->p_page);
+#endif
+	return 0;
+}
+
+/*
+ * Swap ourself in: must be on the swap stack when we do this
+ */
+void swapin(ptptr p)
+{
+	uint16_t blk = p->p_page2 * SWAP_SIZE;
+	uint16_t base = SWAPBASE;
+	uint16_t size = (0x4000 - SWAPBASE) >> 9;
+
+#ifdef DEBUG
+	kprintf("Swapin %x, %d\n", p, p->p_page);
+#endif
+	if (!p->p_page) {
+		kprintf("%x: nopage!\n", p);
+		return;
+	}
+
+	/* Return our swap */
+	swapmap_add(p->p_page2);
+
+	/* This may need other tweaks as its a special nasty case where
+	   we don't want to overwrite the live stack but buffer and fix up
+	   in tricks.s */
+#ifdef CONFIG_HAS_LOW_PAGE
+	swapread(SWAPDEV, blk, 1, 0x0000);
+	blk++;
+#endif
+
+	swapproc = p;		/* always ourself */
+	for (i = 0; i < 4; i ++) {
+		swapread(SWAPDEV, blk, size, base);
+		base += 0x4000;
+		/* Last bank is determined by SWAP SIZE. We do the maths
+		   in 512's (0x60 = 0xC000) */
+		if (i == 3)
+			size = SWAP_SIZE_EXCL_ZP - 0x60;
+		else
+			size = 0x20;	/* 16 K */
+	}
+#ifdef DEBUG
+	kprintf("%x: swapin done %d\n", p, p->p_page);
+#endif
+}
+#endif
+
 #endif