Docs - Mednonogova decompressor based on LZ compression.
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Decompressor Mednonogova, used, apparently, in "Black Crow" is
curious that the bit stream into its format is missing -
although based on LZ compression. Due to this, there is some
advantage in speed and a loss in density.
The text comments: yellow - author, green - are mine.
; Decompressor for v 3.01
; HL-DE-how to
; DLPCB DEFM "v301"
DELPZ PUSH DE
LD DE, DLPCB
LD BC, 4
LDIR
POP DE
xpD0 LD A, (HL)
SRL A
JR NC, xpD1
CALL xpSUB; short copy
RRA;% AAAlenB1
RL B; ^ ^ ^ nopacked
AND 7
xpM2 JR NZ, xpNex; len <= 9
LD A, (HL); len> 9
INC HL
xpNex LD C, (HL); disp (given B)
INC HL
PUSH HL
LD H, D
LD L, E
SBC HL, BC
LD B, 0
LD C, A
xpM1 INC BC
INC BC;> = 3
LDIR
POP HL
EX AF, AF '
JR Z, xpD0
JR NZ, xpDRR; nocompr 1 .. 7
xpD1 RRA
JR C, xpZ1
RRA
JR C, xpZ2
JR Z, xpDEND;% xxxxx000
INC HL
xpDRR LD B, A; nocompr 1 .. 31
xpDL0 LD A, (HL)
INC HL
XOR (HL)
LD (DE), A
INC DE
DJNZ xpDL0
JR xpD0
xpZ2 SRL A;% xxxxx100; repeat
JR C, xpZ2L
LD C, A
XOR A
EX AF, AF '
xpZ22 INC HL
PUSH HL
LD H, D
LD L, E
DEC HL
JR xpM1
xpZ2L CALL xpSUB;% xxxX1100
RRA; ^
RL B; 0 / 1
LD C, (HL)
JR xpZ22
xpZ1 SRL A;% xxxxxx10
JR NC, xpTWO
LD C, A;% xxxxx110; long copy
INC HL
LD A, (HL)
AND # 1F
LD B, A
LD A, C
CALL xpSUB
OR A
JR xpM2
xpTWO INC A; two bytes% xxxxx010
LD C, A; = 1 .. 32
INC HL
PUSH HL
LD H, D
LD L, E
SBC HL, BC
LD C, 2
LDIR
POP HL
JR xpD0
xpDEND LD HL, DLPCB;% xxxxx000
LD C, 4
LDIR
RET
xpSUB EX AF, AF '; Place 3 st.bita current byte in the A'
LD A, (HL)
RLCA
RLCA
RLCA
AND 7
EX AF, AF '
INC HL
RET
--------------------------------------------------
------------- Did you know that ...
By volume of 5.25 "and 3.5" floppy disks hold roughly the same
space - 27.5 cubic centimeters? Dimensions of the first
carrier, however, is overestimated (in fact it is not a square
and a few millimmetrov less). The second is - somewhat
underestimated in one of the measurements (actually 90 x 94 x
3,25 mm).
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Docs - Mednonogova decompressor based on LZ compression.
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