From d83022667779b6c382d5d423d606126aa0a9fec8 Mon Sep 17 00:00:00 2001
From: Alan Cox <alan@linux.intel.com>
Date: Fri, 16 Jan 2015 17:54:17 +0000
Subject: [PATCH] usermem_6502: add uzero, uputc and uputw

Still need to do uget, uput and ugets
---
 Kernel/usermem_std-6502.s | 53 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 49 insertions(+), 4 deletions(-)

diff --git a/Kernel/usermem_std-6502.s b/Kernel/usermem_std-6502.s
index d14f686e..d192dd5b 100644
--- a/Kernel/usermem_std-6502.s
+++ b/Kernel/usermem_std-6502.s
@@ -6,7 +6,8 @@
 		.export __uput, __uputc, __uputw, __uzero
 
 		.import map_kernel, map_process_always
-
+		.import popax
+		.importzp ptr1, tmp1
 ;
 ;	TO DO: Possibly easier to write them in C with just the _c helpers
 ;	but for speed would be best the block ones are asm.
@@ -38,6 +39,50 @@ __ugetw:	sta ptr1
 
 __ugets:	rts
 __uput:		rts
-__uputc:	rts
-__uputw:	rts
-__uzero:	rts
+
+__uputc:	sta ptr1
+		stx ptr1+1
+		jsr map_process_always
+		jsr popax
+		ldy #0
+		sta (ptr1),y
+		jmp map_kernel
+
+__uputw:	sta ptr1
+		stx ptr1+1
+		jsr map_process_always
+		jsr popax
+		ldy #0
+		sta (ptr1),y
+		txa
+		iny
+		sta (ptr1),y
+		jmp map_kernel
+
+__uzero:	sta tmp1
+		stx tmp1+1
+		jsr map_process_always
+		jsr popax		; ax is now the usermode address
+		sta ptr1
+		stx ptr1+1
+
+		ldy #0
+		tya
+
+		ldx tmp1+1		; more than 256 bytes
+		beq __uzero_tail	; no - just do dribbles
+__uzero_blk:
+		sta (ptr1),y
+		iny
+		bne __uzero_blk
+		inc ptr1+1		; next 256 bytes
+		dex			; are we done with whole blocks ?
+		bne __uzero_blk
+
+__uzero_tail:
+		cpy tmp1
+		beq __uzero_done
+		sta (ptr1),y
+		iny
+		bne __uzero_tail
+__uzero_done:	rts
-- 
2.34.1