hexed: vram transfer + early pc transfers

[megadrive.git] / hexed / transfer.S

diff --git a/hexed/transfer.S b/hexed/transfer.S
index 1ac2d62..ef5bf5d 100644 (file)
--- a/hexed/transfer.S
+++ b/hexed/transfer.S
@@ -120,10 +120,23 @@ recv_ad:
        move.l          d2,d0
        rts
 
+# send 1 byte in d0
+#  in: a1 - data port
+#  trash: d1,d2
 send_byte:
        send_one_byte
        rts
 
+.macro switch_to_output
+0: /*Lwait_tl_low: PC should switch to rx mode before lowering tl */
+       move.b          (a1),d0
+       btst.b          #4,d0
+       bne             0b /*Lwait_tl_low*/
+
+       move.b          #0x4f,(0xa1000b).l
+       move.b          #0x40,(a1)
+.endm
+
 .equ sat_maxsize, (80*8+0x200) /* sprites+max_align */
 
 # make sure cache is invalidated
@@ -185,6 +198,7 @@ jumptab:
        bra             pcc_jump
        bra             pcc_io
        bra             pcc_loadstate
+       bra             pcc_vram_send
        bra             pcc_test_code
 
 
@@ -210,13 +224,7 @@ pcc_transfer_send:
        bsr             recv_ad
        move.l          d0,d3
 
-0: /*Lwait_tl_low: it should switch to rx mode before lowering tl */
-       move.b          (a1),d0
-       btst.b          #4,d0
-       bne             0b /*Lwait_tl_low*/
-
-       move.b          #0x4f,(0xa1000b).l
-       move.b          #0x40,(a1)
+       switch_to_output
 
 tr_send_loop:
        move.b          (a0)+,d0
@@ -292,13 +300,7 @@ pcc_io_w32:
        bra             pcc_io_loop
 
 pcc_io_rx:
-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)
+       switch_to_output
 
        cmp.b           #IOSEQ_R32, d3
        beq             pcc_io_r32
@@ -402,6 +404,26 @@ tr_do_vdpreg_loop:
        bra             return
 
 
+pcc_vram_send:
+       /* write VRAM */
+       move.l          #0xc00000,a0
+       move.w          #0x8f02,4(a0)           /* auto increment 2 */
+       move.l          #0,4(a0)                /* VRAM read, addr 0 */
+       move.l          #0x10000/2-1,d4
+
+       switch_to_output
+
+tr_vram_send_loop:
+       move.w          (a0),d3
+       move.w          d3,d0
+       lsr.w           #8,d0
+       bsr             send_byte
+       move.b          d3,d0
+       bsr             send_byte
+       dbra            d4,tr_vram_send_loop
+
+       bra             return
+
 
 
 /* some random code */
@@ -418,7 +440,8 @@ return:
        move.l          d2,(a1)+
        move.l          d3,(a1)+
        move.l          a0,(a1)+
-       bra             return_to_main
+       rts
+#      bra             return_to_main
 
 
 # vim:filetype=asmM68k