Programming Blitter

BLTCON

15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0		15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
ASH				usea	useb	usec	used	LF									BSH				0	0	0	0	doff	0	0	efe	ife	fci	desc	0

(normal mode)

ASH: shift value of source A
USEA: use source A
USEB: use source B
USEC: use source C
USED: use destination D
LF: performed logic function minterm select lines
BSH: shift value of source B
DOFF
EFE: exclusive fill
IFE: inclusive fill
FCI: fill carry input
DESC: descending address mode

15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0		15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
START				1	0	1	1	LF									TEXTURE				0	0	0	0	sign	0	0	sud	sul	aul	sing	1

(line mode)

START: sttarting point of line
LF: performed logic function minterm select lines
TEXTURE:
SIGN: sign flag
SUD: sometimes up or down
SUL: sometimes up or left
AUL: always up or left
SING:single bit per horizontal line (for filling)

BLTSIZE, BLTSIZEV, BLTSIZEH

15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
h										w

h: height in vertical lines
w: width in horizontal pixels

Blitter's Registers

BLTCON	040	2 words
BLTAFWM	044	word
BLTALWM	046	word
BLTCPT	048	2 words
BLTBPT	04E	2 words
BLTAPT	050	2 words
BLTDPT	054	2 words
BLTSIZE	058	word
BLTCONSIZV	05C	word
BLTCONSIZH	05E	word
BLTCMOD	060	word
BLTBMOD	062	word
BLTAMOD	064	word
BLTDMOD	066	word