From: Alan Cox <alan@linux.intel.com>
Date: Fri, 8 Feb 2019 21:40:15 +0000 (+0000)
Subject: r2k: initial usermem
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=32bcb374b61d0cd4b642f63f3a9c923024002fe0;p=FUZIX.git

r2k: initial usermem

This can be optimized a lot it's basically just a Z80 copy for now
---

diff --git a/Kernel/usermem_std-r2k.s b/Kernel/usermem_std-r2k.s
new file mode 100644
index 00000000..3c761c7d
--- /dev/null
+++ b/Kernel/usermem_std-r2k.s
@@ -0,0 +1,167 @@
+;
+;	A generic implementation for now. We can probably do far better
+;	using LDP.
+;
+;	TODO: optimize by using r2k instructions - we can ld hl,4(ix) for
+;	example in one go
+;
+        .module usermem
+
+	.include "platform/kernel.def"
+        .include "kernel-rabbit.def"
+
+        ; exported symbols
+        .globl __uget
+        .globl __ugetc
+        .globl __ugetw
+
+	.globl outcharhex
+	.globl outhl
+
+        .globl __uput
+        .globl __uputc
+        .globl __uputw
+        .globl __uzero
+
+	.globl  map_process_always
+	.globl  map_kernel
+;
+;	We need these in common as they bank switch
+;
+        .area _COMMONMEM
+
+uputget:
+        ; load DE with the byte count
+        ld e, 8(ix) ; byte count
+        ld d, 9(ix)
+	ld a, d
+	or e
+	ret z		; no work
+	dec de		; we return BC as a count for two 8bit loops
+	ld b, e		; not a 16bit value
+	inc b		; See http://map.grauw.nl/articles/fast_loops.php
+	inc d
+	ld c, d
+        ; load HL with the source address
+        ld l, 4(ix) ; src address
+        ld h, 5(ix)
+        ; load DE with destination address (in userspace)
+        ld e, 6(ix)
+        ld d, 7(ix)
+	ld a, b
+	or c
+	ret
+
+__uputc:
+	pop bc	;	return
+	pop de	;	char
+	pop hl	;	dest
+	push hl
+	push de
+	push bc
+	call map_process_always
+	ld (hl), e
+uputc_out:
+	jp map_kernel			; map the kernel back below common
+
+__uputw:
+	pop bc	;	return
+	pop de	;	word
+	pop hl	;	dest
+	push hl
+	push de
+	push bc
+	call map_process_always
+	ld (hl), e
+	inc hl
+	ld (hl), d
+	jp map_kernel
+
+__ugetc:
+	pop bc	; return
+	pop hl	; address
+	push hl
+	push bc
+	call map_process_always
+        ld l, (hl)
+	ld h, #0
+	jp map_kernel
+
+__ugetw:
+	pop bc	; return
+	pop hl	; address
+	push hl
+	push bc
+	call map_process_always
+        ld a, (hl)
+	inc hl
+	ld h, (hl)
+	ld l, a
+	jp map_kernel
+
+__uput:
+	push ix
+	ld ix, #0
+	add ix, sp
+	call uputget			; source in HL dest in DE, count in BC
+	jr z, uput_out			; but count is at this point magic
+	
+uput_l:	ld a, (hl)
+	inc hl
+	call map_process_always
+	ld (de), a
+	call map_kernel
+	inc de
+	djnz uput_l
+	dec c
+	jr nz, uput_l
+
+uput_out:
+	pop ix
+	ld hl, #0
+	ret
+
+
+__uget:
+	push ix
+	ld ix, #0
+	add ix, sp
+	call uputget			; source in HL dest in DE, count in BC
+	jr z, uput_out			; but count is at this point magic
+	
+uget_l:
+	call map_process_always
+	ld a, (hl)
+	inc hl
+	call map_kernel
+	ld (de), a
+	inc de
+	djnz uget_l
+	dec c
+	jr nz, uget_l
+	jr uput_out
+
+;
+__uzero:
+	pop de	; return
+	pop hl	; address
+	pop bc	; size
+	push bc
+	push hl	
+	push de
+	ld a, b	; check for 0 copy
+	or c
+	ret z
+	call map_process_always
+	ld (hl), #0
+	dec bc
+	ld a, b
+	or c
+	jp z, uputc_out
+	ld e, l
+	ld d, h
+	inc de
+wiper:
+	ldi
+	jp lo,wiper
+	jp uputc_out