***************************************************************************** * * * Ass-Subroutine to convert packed STAD-Pictures to 32k pictures (normal * * screenformat). * * * * params: (sp) LONG return-adress * * 4(sp) LONG adress of packed STAD-pictures * * 8(sp) LONG adress of destination (32k buffer) * * * * returns: d0 0 = did correct convert * * 1 = pictures is not in packed STAD-format :-( * * * * important: the two adresses are not removed from the stack (like trap) * * * * History: * * Version 1.0 01.06.1991 Wolfgang Ley * * - first version * * Version 1.1 03.06.1991 Wolfgang Ley * * - saving registers now * * Version 1.2 05.06.1991 Wolfgang Ley * * - extra-counter in v_lese removed * * Version 1.3 06.07.1992 Wolfgang Ley * * - code cleaned up * * * ***************************************************************************** GLOBL fromstad TEXT fromstad: movem.l D1-D5/A0-A1,-(SP) ;save registers movea.l 32(SP),A0 ;adress of packed STAD-picture movea.l 36(SP),A1 ;adress of destination (32k) ; --------------------------------------------------------------------------- ; STAD-Header: ; Byte 1-4 string 'pM85' (horizontal packed) ; 'pM86' (vertical packed) ; Byte 5 ID-Byte ; Byte 6 PACK-Byte ; Byte 7 SPECIAL-Byte ; .... picture datas ; --------------------------------------------------------------------------- move.b 4(A0),D1 ;read ID-byte move.b 5(A0),D2 ;read PACK-byte move.b 6(A0),D3 ;read SPEC-byte clr.w D4 ;clear dest.offset cmpi.b #'p',(A0)+ ;first byte = "p" bne.b error cmpi.b #'M',(A0)+ ;second byte = "M" bne.b error cmpi.b #'8',(A0)+ ;third byte = "8" bne.b error cmpi.b #'5',(A0) ;fourth byte = "5" beq.b h_start ;-> horizontal packed cmpi.b #'6',(A0) ;fourth byte = "6" beq.b v_start ;-> vertical packed error: move.l #1,D0 ;error 1 = no packed STAD-picture exit: movem.l (SP)+,D1-D5/A0-A1 ;restore registers rts ; --------------------------------------------------------------------------- ; horizontal decompress routine ; --------------------------------------------------------------------------- h_start: addq.l #4,A0 ;length of header h_read: move.b (A0)+,D0 ;read next byte cmp.b D1,D0 ;ID-Byte? beq.b h_use_pack ;yes -> use PACK-byte cmp.b D3,D0 ;SPEC-Byte? beq.b h_use_spec ;yes -> use SPEC-byte move.b D0,0(A1,D4.w) ;use Byte "as is" addq.w #1,D4 ;increment offset h_cont: cmpi.w #32000,D4 ;everything read in? bne.b h_read ;no -> read next ready: clr.l D0 ;return 0 = everything ok bra.b exit ;that's it... ; --------------------------------------------------------------------------- ; if you got an ID-byte: read next byte (n) and use PACK-Byte n+1 times ; --------------------------------------------------------------------------- h_use_pack: move.b D2,D5 ;PACK-byte to write-byte bra.b h_unpack ;...and unpack ; --------------------------------------------------------------------------- ; if you got a SPEC-byte: read two more byte (d and n) and use the byte d ; n+1 times ; --------------------------------------------------------------------------- h_use_spec: move.b (A0)+,D5 ;read next byte d h_unpack: clr.w D0 ;clear... move.b (A0)+,D0 ;read quantity h_unpack_1: move.b D5,0(A1,D4.w) ;write byte addq.w #1,D4 cmpi.w #32000,D4 ;ready? dbeq D0,h_unpack_1 ;next turn... bra.b h_cont ;read next byte from source ; --------------------------------------------------------------------------- ; verticale decompress routine ; --------------------------------------------------------------------------- v_start: addq.l #4,A0 ;don't read header v_read: move.b (A0)+,D0 ;read byte cmp.b D1,D0 ;ID-Byte? beq.b v_use_pack ;yes -> use PACK-byte cmp.b D3,D0 ;SPEC-Byte? beq.b v_use_spec ;yes -> use SPEC-byte move.b D0,0(A1,D4.w) ;use byte "as is" addi.l #80,D4 ;increment offset cmpi.w #32000,D4 ;column ready? blo.b v_read ;no, continue read subi.w #31999,D4 ;correct offset to next column cmpi.w #80,D4 ;everything read in? bne.b v_read ;no, continue read bra.b ready ;yes -> ready ; --------------------------------------------------------------------------- ; ...bee h_use_pack ; --------------------------------------------------------------------------- v_use_pack: move.b D2,D5 ;PACK-byte to write-byte bra.b v_unpack ;...and unpack v_use_spec: move.b (A0)+,D5 ;read next byte d v_unpack: clr.w D0 ;clear... move.b (A0)+,D0 ;read quantity v_unpack_1: move.b D5,0(A1,D4.w) ;write byte addi.l #80,D4 ;increment offset cmpi.w #32000,D4 ;column complete? blo.b v_unpack_2 ;no, continue read subi.w #31999,D4 ;yes, correct offset to next column cmpi.w #80,D4 ;everything read in? beq.b ready ;yes, ready v_unpack_2: dbra D0,v_unpack_1 ;...next turn bra.b v_read ;read next byte from source END