--- /dev/null
+###############################################################################
+#
+# Copyright (c) 2011, GraÅžvydas Ignotas
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+# * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+# * Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in the
+# documentation and/or other materials provided with the distribution.
+# * Neither the name of the organization nor the
+# names of its contributors may be used to endorse or promote products
+# derived from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED ''AS IS'' AND ANY
+# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL <copyright holder> BE LIABLE FOR ANY
+# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+# Assemble with gas
+# --register-prefix-optional --bitwise-or
+#
+
+#include "transfer.h"
+
+.text
+.globl do_transfer
+
+
+# receive 1 byte to d0
+# in: a1 - data port
+# trash: d1
+.macro recv_one_byte is_last=0
+ move.b #0,(a1) /* clear TH */
+
+0: /*L_wait_tl_low*/
+ move.b (a1),d1
+ btst.b #4,d1
+ bne 0b /*L_wait_tl_low*/
+
+ move.b #0x40,(a1) /* set TH */
+ and.b #0x0f,d1
+
+0: /*L_wait_tl_hi*/
+ move.b (a1),d0
+ btst.b #4,d0
+ beq 0b /*L_wait_tl_hi*/
+
+.if !\is_last
+ move.b #0,(a1) /* clear TH - ready for next */
+.endif
+ lsl.b #4,d0
+ or.b d1,d0
+.endm
+
+# send 1 byte in d0
+# in: a1 - data port
+# trash: d1,d2
+.macro send_one_byte
+ move.b d0,d2
+ and.b #0x0f,d2
+
+0: /*Lwait_tl_low:*/
+ move.b (a1),d1
+ btst.b #4,d1
+ bne 0b /*Lwait_tl_low*/
+
+ move.b d2,(a1) /* clears TH and writes data */
+
+ move.b d0,d2
+ lsr.b #4,d2
+ bset.b #6,d2 /* prepare TH */
+
+0: /*wait_tl_hi*/
+ move.b (a1),d1
+ btst.b #4,d1
+ beq 0b /*wait_tl_hi1*/
+
+ move.b d2,(a1)
+.endm
+
+recv_byte:
+ recv_one_byte 1
+ rts
+
+# receive address/size to d0 (3 bytes BE)
+# in: a1 - data port
+# trash: d1,d2
+recv_ad:
+ moveq.l #0,d2
+ bsr recv_byte
+ move.b d0,d2
+ bsr recv_byte
+ lsl.l #8,d2
+ move.b d0,d2
+ bsr recv_byte
+ lsl.l #8,d2
+ move.b d0,d2
+ move.l d2,d0
+ rts
+
+
+do_transfer:
+ lea 0xa10005,a1
+ move.b #0x40,(0xa1000b).l /* ctrl - all inputs except TH */
+ move.b #0x00,(a1)
+
+ bsr recv_byte
+ cmp.b #CMD_PREFIX,d0
+ bne return
+
+ bsr recv_byte
+ cmp.b #CMD_MD_SEND,d0 /* sent to us */
+ beq transfer_recv
+ cmp.b #CMD_MD_RECV,d0 /* recv from us */
+ beq transfer_send
+ bra return
+
+
+transfer_recv:
+ bsr recv_ad
+ move.l d0,a0
+ bsr recv_ad
+ move.l d0,d3
+
+tr_recv_loop:
+ recv_one_byte
+ move.b d0,(a0)+
+ subq.l #1,d3
+ bne tr_recv_loop
+ bra return
+
+transfer_send:
+ bsr recv_ad
+ move.l d0,a0
+ bsr recv_ad
+ move.l d0,d3
+
+0: /*Lwait_tl_low:*/
+ move.b (a1),d0
+ btst.b #4,d0
+ bne 0b /*Lwait_tl_low*/
+
+ move.b #0x4f,(0xa1000b).l
+ move.b #0x40,(a1)
+
+tr_send_loop:
+ move.b (a0)+,d0
+ send_one_byte
+ subq.l #1,d3
+ bne tr_send_loop
+ bra return
+
+
+return:
+ move.b #0,(0xa1000b).l /* all inputs */
+ move.l #0xffe000,a1
+ move.l d0,(a1)+ /* last state for debug */
+ move.l d1,(a1)+
+ move.l d2,(a1)+
+ move.l d3,(a1)+
+ move.l a0,(a1)+
+ bra return_to_main
+
+
+# vim:filetype=asmM68k
notaz.gp2x.de / megadrive.git / blobdiff