From: Alan Cox <alan@linux.intel.com>
Date: Thu, 19 Oct 2017 21:59:03 +0000 (+0100)
Subject: 8086: add the page clear and copy logic
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=6956112d5daa140b6e7b09f57121ed4be1c4f31b;p=FUZIX.git

8086: add the page clear and copy logic

Fast 4K copy and clear routines for shuffling memory
---

diff --git a/Kernel/bank8086.c b/Kernel/bank8086.c
index 6397aa1c..59cb6276 100644
--- a/Kernel/bank8086.c
+++ b/Kernel/bank8086.c
@@ -60,6 +60,10 @@
 
 #ifdef CONFIG_BANK_8086
 
+/* private : asm helpers */
+extern void do_copy_page(uint16_t, uint16_t);
+extern void do_zero_page(uint16_t);
+
 typedef uint8_t page_t;
 
 /* Assuming a 640K PC/XT. This model needs some work to handle a 16MB 286
@@ -224,6 +228,21 @@ static int do_process_create(uint8_t csize, uint8_t dsize, uint8_t ssize)
 	return 0;
 }
 
+static void copy_pages(page_t to, page_t from, uint16_t len)
+{
+	uint16_t ts = page_to_segment(to);
+	uint16_t fs = page_to_segment(from);
+	while(len--)
+		do_copy_page(ts++, fs++);
+}
+
+static void zero_pages(page_t to, uint16_t len)
+{
+	uint16_t ts = page_to_segment(to);
+	while(len--)
+		do_zero_page(ts++);
+}
+
 /*
  *	A brk() or stack grow has collided with some other piece of memory.
  *	Try and find a place to move our data and stacks so that they can
diff --git a/Kernel/lowlevel-8086.S b/Kernel/lowlevel-8086.S
index 8c1d3910..131b62da 100644
--- a/Kernel/lowlevel-8086.S
+++ b/Kernel/lowlevel-8086.S
@@ -14,6 +14,9 @@
 	.global set_irq
 	.global	cpu_detect
 
+	.global copy_to_far
+	.global copy_from_far
+
 	/* GCC glue */
 	.global __ashrsi3
 	.global	__ashlsi3
@@ -413,6 +416,57 @@ always_16bit:
 	movb	$16,bus_width
 	ret
 
+/*
+ *	Handy routines for block copying to/from far memory. These
+ *	are not optimized. We should be smarter about using movsw
+ *	and alignment on 8086+
+ *
+ *	Warning: don't use prefixes with rep as we have to run on 8086
+ *
+ *	copy_to_far(int16_t seg, int16_t to, void *from, int16_t len)
+ *	copy_from_far(int16_t seg, void *to, int16_t from, int16_t len)
+ */
+
+copy_to_far:
+	pushw	%bp
+	movw	%sp,%bp
+	pushw	%es
+	pushw	%si
+	pushw	%di
+	pushw	%ds
+	movw	4(%bp),%ax
+	movw	%ax,%es
+copier:
+	movw	6(%bp),%di
+	movw	8(%bp),%si
+	movw	10(%bp),%ax
+	movw	%ax,%cx
+	shr	%cx
+	jz	noblock
+	rep	movsw
+noblock:
+	testb	$1,%al
+	jne	nofinal
+	movsb
+nofinal:
+	popw	%ds
+	popw	%di
+	popw	%si
+	popw	%es
+	popw	%bp
+	ret
+
+copy_from_far:
+	pushw	%bp
+	movw	%sp,%bp
+	pushw	%es
+	pushw	%si
+	pushw	%di
+	pushw	%ds
+	movw	4(%bp),%ax
+	movw	%ax,%ds
+	jmp	copier
+
 /* FIXME: extract from C library or write nice ones */
 __ashlsi3: