From: Alan Cox <alan@linux.intel.com>
Date: Tue, 26 Jul 2016 10:18:41 +0000 (+0100)
Subject: trs80: first cut at dw_transaction
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=5bc0be69c02e21664560e9a834cf85e439e222c5;p=FUZIX.git

trs80: first cut at dw_transaction
---

diff --git a/Kernel/platform-trs80/drivewire.s b/Kernel/platform-trs80/drivewire.s
index b0ab7cbd..3604e75f 100644
--- a/Kernel/platform-trs80/drivewire.s
+++ b/Kernel/platform-trs80/drivewire.s
@@ -1,19 +1,67 @@
 	.module drivewire
 
 	.globl _dw_operation
+	.globl _dw_transaction
 	.globl _dw_reset
 
 	.globl map_process_a
+	.globl map_process_always
 	.globl map_kernel
 
 
 
 	.area _COMMONMEM
 
+;
+;	Implement dw_transaction for the TRS80 port
+;
+_dw_transaction:
+	push ix
+	ld ix,#0
+	add ix,sp
+	ld a,-10(ix)
+	or a
+	push af
+	call nz, map_process_always
+	ld h,-2(ix)
+	ld l,-3(ix)
+	ld b,-4(ix)
+	ld c,-5(ix)
+	ld de, #txbyte
+	call dw_op
+	ld h,-6(ix)
+	ld l,-7(ix)
+	ld b,-8(ix)
+	ld c,-9(ix)
+	ld de, #rxbyte
+	call dw_op
+	ld hl, #0
+	jr nc, read_good
+	; We don't distinguish framing and short frames FIXME
+	dec hl
+read_good:
+	pop af
+	call nz, map_kernel
+	pop ix
+	ret
+
 	; dw_reset(driveptr)
 _dw_reset:
 	ret
 
+dw_op:
+	ld (op + 1),de
+dw_op_loop:
+	ld a,b
+	or c
+	ret z
+op:	call rxbyte		; self modifies
+	ret c
+	ld (hl),a
+	inc hl
+	dec bc
+	jr dw_op_loop
+
 	; dw_operation(cmdblock)
 _dw_operation:
 	pop bc		; return