vdp1: do proper interrupt blocking

This fixes the odd very weird happening because the TMS9918A data pointer is
messed up by register accesses (eg interrupts mid scroll). Also fix the
timing for MSX1. We can't quite otir/inir a TMS9918A on MSX but must use
outi ; jp nz in order to run at the required access rate.

diff --git a/Kernel/dev/vdp1.s b/Kernel/dev/vdp1.s
index 07d0629..d6a2be6 100644 (file)
--- a/Kernel/dev/vdp1.s
+++ b/Kernel/dev/vdp1.s
@@ -10,6 +10,8 @@
            .globl cursor_off
            .globl cursorpos
 
+           .globl _int_disabled
+
            .globl _vdpport
 
            .globl vdpinit
@@ -79,6 +81,9 @@ plot_char:  pop hl
            push bc
            push de
            push hl
+           ld a,(_int_disabled)
+           push af
+           di
 plotit:
            ld b, #0x40                 ; writing
            call videopos
@@ -89,6 +94,11 @@ plotit2:
            out (c), h                  ; address | 0x40
            dec c
            out (c), a                  ; character
+popret:
+           pop af
+           or a
+           ret nz
+           ei
            ret
 
 ;
@@ -110,7 +120,9 @@ scrollbuf:   .ds            40
 _scroll_down:
                .endif
 scroll_down:
-           ret
+           ld a,(_int_disabled)
+           push af
+           di
            ld b, #23
            ld de, #0x3C0       ; start of bottom line
 upline:
@@ -120,7 +132,9 @@ upline:
            out (c), e          ; our position
            out (c), d
            dec c
-           inir                ; safe on MSX2 but not MSX1? - FIXME 
+down_0:
+           ini
+           jp nz, down_0
            inc c
            ld hl, #0x4028      ; go down one line and into write mode
            add hl, de          ; relative to our position
@@ -129,18 +143,23 @@ upline:
            ld b, #0x28
            ld hl, #scrollbuf
            dec c
-           otir                ; video ptr is to the line below so keep going
+down_1:
+           outi                ; video ptr is to the line below so keep going
+           jp nz,down_1
            pop bc              ; recover line counter
            ld hl, #0xffd8
            add hl, de          ; up 40 bytes
            ex de, hl           ; and back into DE
            djnz upline
-           ret
+           jp popret
 
                .if VDP_DIRECT
 _scroll_up:
                .endif
 scroll_up:
+           ld a,(_int_disabled)
+           push af
+           di
            ld b, #23
            ld de, #40          ; start of second line
 downline:   push bc
@@ -149,7 +168,9 @@ downline:   push bc
            out (c), e
            out (c), d
            dec c
-           inir                ; MSX1 fixme ?
+up_0:
+           ini
+           jp nz, up_0
            inc c
            ld hl, #0x3FD8      ; up 40 bytes in the low 12 bits, add 0x40
                                ; for write ( we will carry one into the top
@@ -160,13 +181,15 @@ downline:   push bc
            dec c
            ld hl, #scrollbuf
            ld b, #0x40
-           otir                ; FIXME: is otir ok for MSX 1 ???
+up_1:
+           outi
+           jp nz,up_1
            pop bc
            ld hl, #40
            add hl, de
            ex de, hl
            djnz downline
-           ret
+           jp popret
 
                .if VDP_DIRECT
 _clear_lines:
@@ -176,6 +199,9 @@ clear_lines:
            pop de      ; E = line, D = count
            push de
            push hl
+           ld a,(_int_disabled)
+           push af
+           di
            ld c, d
            ld d, #0
            ld b, #0x40
@@ -195,7 +221,7 @@ l1:     out (c), a          ; Inner loop clears a line, outer counts
             djnz l1
            dec e
            jr nz, l2
-           ret
+           jp popret
 
                .if VDP_DIRECT
 _clear_across:
@@ -207,6 +233,9 @@ clear_across:
            push bc
            push de
            push hl
+           ld a,(_int_disabled)
+           push af
+           di
            ld b, #0x40
            call videopos
            ld a, c
@@ -218,7 +247,7 @@ clear_across:
            dec c
 l3:        out (c), a
             djnz l1
-           ret
+           jp popret
 
 ;
 ;      FIXME: should use attribute blink flag not a char
@@ -231,6 +260,9 @@ cursor_on:
            pop de
            push de
            push hl
+           ld a,(_int_disabled)
+           push af
+           di
            ld (cursorpos), de
            ld b, #0x00                 ; reading
            call videopos
@@ -249,10 +281,14 @@ cursor_on:
 _cursor_off:
                .endif
 cursor_off:
+           ld a,(_int_disabled)
+           push af
+           di
            ld de, (cursorpos)
            ld a, (cursorpeek)
            ld c, a
-           call plotit
+           jp plotit
+
 _vtattr_notify:
            ret