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Created page with "<pre> ;--------------------------------------------------------------------- ; 256 byte Overscan MegaText Intro v1.1b ; (7DX Demo Party 2011 Release) ; ; for Amstrad 464/664..."
<pre>
;---------------------------------------------------------------------
; 256 byte Overscan MegaText Intro v1.1b
; (7DX Demo Party 2011 Release)
;
; for Amstrad 464/664/6128 computers
;
; by matahari - (Dec 24, 2011)
;
; Featuring;
; - Greetings message via 50Hz CRTC hardware scroll
; - 100% overscan (full) screen size
; - Complete Amstrad palette (27 colours) on screen at once
; - And, all in 256 bytes!
;---------------------------------------------------------------------
LET ADDR_Start = &400
LET ADDR_TextMap = ADDR_Start + 256
LET CONST_TotalRasterLines = 269
LET VAR_BgrndColour = ADDR_Start - 1
LET VAR_FlipFlop = VAR_BgrndColour - 1
LET VAR_LineSkipMinus = CONST_TotalRasterLines * -9
LET VAR_LineSkipPlus = CONST_TotalRasterLines * 9
VAR_XOR equ 1 xor 0
run start
org ADDR_Start
start: ;--------- Generate a dummy interrupt handler ---------------------------
ld hl,&c9fb
ld (&0038),hl
;--------- Set CRTC Registers -------------------------------------------
ld hl,CRTC_Data
loopCRTC: ld a,(hl)
ld b,&bc + 1
outi
ld b,&bd + 1
outi
inc a
jr nz,loopCRTC
;--------- Display text message -----------------------------------------
ld hl,ADDR_TextMap
ld de,Message
loopText: push de
push hl
ld a,2
call &bc0e
pop hl
pop de
ld a,(de)
cp 255
jr z,loopExec
call &bb5a
inc de
push de
;--------- Grab pixels of displayed char --------------------------------
ld de,&c000
ld a,8
ld c,&40
outer: ex af,af'
ld iy,vangelis + 1
ld (iy),%10000000
call Proc_FlipFlop
inner: call Proc_FlipFlop
or a
jr z,bitBckgrndA
ld a,&55
jr bitBckgrndB
bitBckgrndA: ld a,&57
bitBckgrndB: ld (VAR_BgrndColour),a
ld a,(de)
vangelis: and 0
jr z,blit
ld a,c
;*********************************
blit: push hl
push de
push bc
ld de,9
ld b,26
blitText: add hl,de
or a
jr z,blitBckgrnd
ld (hl),c
inc c
jr blitSkip
blitBckgrnd: push af
ld a,(VAR_BgrndColour)
ld (hl),a
pop af
blitSkip: djnz blitText
pop bc
pop de
pop hl
;*********************************
inc hl
rr (iy)
jr nc,inner
inc hl
ld a,8
add a,d
ld d,a
push bc
ld bc,25*9
add hl,bc
pop bc
ex af,af'
dec a
jr nz,outer
pop de
jr loopText
;*********************************************************************
; MAIN LOOP - INITIALIZE!
;*********************************************************************
loopExec: ld hl,ADDR_TextMap + VAR_LineSkipPlus
; Checking VBlanking only for once!
; Rest of the code will be manually synced
; via precise t-state calculations.
ld b,&f5
waitVBlanking: in a,(c)
rra
jr nc,waitVBlanking
halt
di
;--------- X-Pos Alignment ----------------------------------------------
ld a,(hl) ; waste time! => 7 cycles
; Aligns perfect on WinApe.
; If you need precise
; alignment on an original Amstrad,
; you need to comment out this line
; OR replace it with a NOP!
; No worries, intro size will not
; exceed 256 bytes either way ;-)
;*********************************************************************
; MAIN LOOP - BEGIN
;*********************************************************************
loopBegin: ld de,VAR_LineSkipMinus + 9
add hl,de
;--------- Wait for perfect sync! ---------------------------------------
ld b,203 ; waste time!
waste1: nop ; waste time!
add ix,ix ; waste time!
djnz waste1 ; waste time!
;--------- Start CRTC code ----------------------------------------------
ld de,CONST_TotalRasterLines
ld bc,&7f00
out (c),c
crash: outi
inc b
outi
inc b
outi
inc b
outi
inc b
outi
inc b
outi
inc b
outi
inc b
outi
inc b
outi
inc b
ld a,(hl) ; waste time!
nop ; waste time!
dec de
ld a,d
or e
jr nz,crash
;--------- Raster colour = Black ----------------------------------------
ld a,&54
out (c),a
nop ; waste time!
ld b,(hl) ; waste time!
ld b,224 ; waste time!
waste2: djnz waste2 ; waste time!
loopEnd: jr loopBegin
;*********************************************************************
; MAIN LOOP - END
;*********************************************************************
;--------- Procedure for Flip/Flop --------------------------------------
Proc_FlipFlop: ld a,(VAR_FlipFlop)
xor VAR_XOR
ld (VAR_FlipFlop),a
ret
;--------- CRTC Data ----------------------------------------------------
CRTC_Data: db 1,54 ; set display width
db 2,50 ; set horizontal sync
db 6,34 ; set display height
db 7,35 ; set vertical sync
db 255 ; => EXIT LOOP
Message: db ' WELCOME TO 7DX2011 ',255
</pre>
;---------------------------------------------------------------------
; 256 byte Overscan MegaText Intro v1.1b
; (7DX Demo Party 2011 Release)
;
; for Amstrad 464/664/6128 computers
;
; by matahari - (Dec 24, 2011)
;
; Featuring;
; - Greetings message via 50Hz CRTC hardware scroll
; - 100% overscan (full) screen size
; - Complete Amstrad palette (27 colours) on screen at once
; - And, all in 256 bytes!
;---------------------------------------------------------------------
LET ADDR_Start = &400
LET ADDR_TextMap = ADDR_Start + 256
LET CONST_TotalRasterLines = 269
LET VAR_BgrndColour = ADDR_Start - 1
LET VAR_FlipFlop = VAR_BgrndColour - 1
LET VAR_LineSkipMinus = CONST_TotalRasterLines * -9
LET VAR_LineSkipPlus = CONST_TotalRasterLines * 9
VAR_XOR equ 1 xor 0
run start
org ADDR_Start
start: ;--------- Generate a dummy interrupt handler ---------------------------
ld hl,&c9fb
ld (&0038),hl
;--------- Set CRTC Registers -------------------------------------------
ld hl,CRTC_Data
loopCRTC: ld a,(hl)
ld b,&bc + 1
outi
ld b,&bd + 1
outi
inc a
jr nz,loopCRTC
;--------- Display text message -----------------------------------------
ld hl,ADDR_TextMap
ld de,Message
loopText: push de
push hl
ld a,2
call &bc0e
pop hl
pop de
ld a,(de)
cp 255
jr z,loopExec
call &bb5a
inc de
push de
;--------- Grab pixels of displayed char --------------------------------
ld de,&c000
ld a,8
ld c,&40
outer: ex af,af'
ld iy,vangelis + 1
ld (iy),%10000000
call Proc_FlipFlop
inner: call Proc_FlipFlop
or a
jr z,bitBckgrndA
ld a,&55
jr bitBckgrndB
bitBckgrndA: ld a,&57
bitBckgrndB: ld (VAR_BgrndColour),a
ld a,(de)
vangelis: and 0
jr z,blit
ld a,c
;*********************************
blit: push hl
push de
push bc
ld de,9
ld b,26
blitText: add hl,de
or a
jr z,blitBckgrnd
ld (hl),c
inc c
jr blitSkip
blitBckgrnd: push af
ld a,(VAR_BgrndColour)
ld (hl),a
pop af
blitSkip: djnz blitText
pop bc
pop de
pop hl
;*********************************
inc hl
rr (iy)
jr nc,inner
inc hl
ld a,8
add a,d
ld d,a
push bc
ld bc,25*9
add hl,bc
pop bc
ex af,af'
dec a
jr nz,outer
pop de
jr loopText
;*********************************************************************
; MAIN LOOP - INITIALIZE!
;*********************************************************************
loopExec: ld hl,ADDR_TextMap + VAR_LineSkipPlus
; Checking VBlanking only for once!
; Rest of the code will be manually synced
; via precise t-state calculations.
ld b,&f5
waitVBlanking: in a,(c)
rra
jr nc,waitVBlanking
halt
di
;--------- X-Pos Alignment ----------------------------------------------
ld a,(hl) ; waste time! => 7 cycles
; Aligns perfect on WinApe.
; If you need precise
; alignment on an original Amstrad,
; you need to comment out this line
; OR replace it with a NOP!
; No worries, intro size will not
; exceed 256 bytes either way ;-)
;*********************************************************************
; MAIN LOOP - BEGIN
;*********************************************************************
loopBegin: ld de,VAR_LineSkipMinus + 9
add hl,de
;--------- Wait for perfect sync! ---------------------------------------
ld b,203 ; waste time!
waste1: nop ; waste time!
add ix,ix ; waste time!
djnz waste1 ; waste time!
;--------- Start CRTC code ----------------------------------------------
ld de,CONST_TotalRasterLines
ld bc,&7f00
out (c),c
crash: outi
inc b
outi
inc b
outi
inc b
outi
inc b
outi
inc b
outi
inc b
outi
inc b
outi
inc b
outi
inc b
ld a,(hl) ; waste time!
nop ; waste time!
dec de
ld a,d
or e
jr nz,crash
;--------- Raster colour = Black ----------------------------------------
ld a,&54
out (c),a
nop ; waste time!
ld b,(hl) ; waste time!
ld b,224 ; waste time!
waste2: djnz waste2 ; waste time!
loopEnd: jr loopBegin
;*********************************************************************
; MAIN LOOP - END
;*********************************************************************
;--------- Procedure for Flip/Flop --------------------------------------
Proc_FlipFlop: ld a,(VAR_FlipFlop)
xor VAR_XOR
ld (VAR_FlipFlop),a
ret
;--------- CRTC Data ----------------------------------------------------
CRTC_Data: db 1,54 ; set display width
db 2,50 ; set horizontal sync
db 6,34 ; set display height
db 7,35 ; set vertical sync
db 255 ; => EXIT LOOP
Message: db ' WELCOME TO 7DX2011 ',255
</pre>
