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1 word descending char blit

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This commit is contained in:
alpine9000
2016-04-01 15:24:44 +11:00
parent 01846c84fb
commit c80864f48a
1 changed files with 9 additions and 33 deletions
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025.scroll_text/blitchar.s
+9 -33
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@@ -4,8 +4,8 @@
DESCENDING equ 1
BLIT_LF_MINTERM equ $ca ; cookie cut
BLIT_WIDTH_WORDS equ 2 ; blit 2 words to allow shifting
BLIT_WIDTH_BYTES equ 4
BLIT_WIDTH_WORDS equ 1 ; blit 2 words to allow shifting
BLIT_WIDTH_BYTES equ BLIT_WIDTH_WORDS*2
FONTMAP_WIDTH_BYTES equ 32
BlitChar8:
@@ -27,12 +27,9 @@ BlitChar8:
move.w #BITPLANE_WIDTH_BYTES-BLIT_WIDTH_BYTES,BLTCMOD(a6) ; C modulo
move.w #BITPLANE_WIDTH_BYTES-BLIT_WIDTH_BYTES,BLTDMOD(a6) ; D modulo
mulu.w #BITPLANE_WIDTH_BYTES*SCREEN_BIT_DEPTH,d1 ; ypos bytes
if DESCENDING==1
move.w #$0000,BLTAFWM(a6) ; mask out extra word used for shifting
else
move.w #$0000,BLTALWM(a6) ; mask out extra word used for shifting
endif
move.w #$ffff,BLTADAT(a6) ; preload source mask so only BLTA?WM mask is used
move.w #$ffff,BLTAFWM(a6) ; mask out extra word used for shifting
move.w #$ffff,BLTADAT(a6) ;??? preload source mask so only BLTA?WM mask is used
move.l #font,a5 ; font pointer
move.l #fontMask,d7 ; font mask pointer
move.w #FONTMAP_WIDTH_BYTES*SCREEN_BIT_DEPTH*FONT_HEIGHT,d3 ; bytes per font line
@@ -89,10 +86,8 @@ DrawChar8:
;; a1 - object
;; a2 - mask
if DESCENDING==1
add.l #(FONT_HEIGHT*SCREEN_BIT_DEPTH*FONTMAP_WIDTH_BYTES)-FONTMAP_WIDTH_BYTES+2,a1
add.l #(FONT_HEIGHT*SCREEN_BIT_DEPTH*FONTMAP_WIDTH_BYTES)-FONTMAP_WIDTH_BYTES+2,a2
endif
add.l #(FONT_HEIGHT*SCREEN_BIT_DEPTH*FONTMAP_WIDTH_BYTES)-FONTMAP_WIDTH_BYTES+0,a1
add.l #(FONT_HEIGHT*SCREEN_BIT_DEPTH*FONTMAP_WIDTH_BYTES)-FONTMAP_WIDTH_BYTES+0,a2
move.l d0,d4 ; xpos
@@ -106,37 +101,19 @@ DrawChar8:
.oddChar
if DESCENDING==1
move.w #$00ff,BLTALWM(a6) ; select the second (odd) character in the word
move.w #$8000,d5
else
subq #8,d5 ; offset the x position for the odd character
move.w #$00FF,BLTAFWM(a6) ; select the second (odd) character in the word
subq #1,a4 ; move the destination pointer left by one byte
endif
bra .continue
.evenChar:
if DESCENDING==1
move.w #$FF00,BLTALWM(a6) ; select the first character in the word
move.w #0,d5
else
move.w #$FF00,BLTAFWM(a6) ; select the first character in the word
endif
.continue:
if DESCENDING==1
ori.l #2,d5
move.w d5,BLTCON1(A6) ; set the shift bits 12-15, bits 00-11 cleared
else
;; this shift will give us the bits to shift (bits 0-3) in bits (12-15) of d5
swap d5 ; d5 << 12
lsr.l #4,d5 ;
move.w d5,BLTCON1(A6) ; set the shift bits 12-15, bits 00-11 cleared
endif;
if MASKED_FONT==1
@@ -151,9 +128,8 @@ DrawChar8:
add.l d4,a4 ; dest += XPOS_BYTES
add.l d1,a4 ; dest += YPOS_BYTES
if DESCENDING==1
add.l #(FONT_HEIGHT*SCREEN_BIT_DEPTH*BITPLANE_WIDTH_BYTES)-BITPLANE_WIDTH_BYTES+2,a4
endif
add.l #(FONT_HEIGHT*SCREEN_BIT_DEPTH*BITPLANE_WIDTH_BYTES)-BITPLANE_WIDTH_BYTES+0,a4
move.l a4,BLTCPTH(a6) ; background top left corner
move.l a4,BLTDPTH(a6) ; destination top left corner