PicoDecomp

#======================================================================
# PICO decompressor
# Tested on Ojamajo/Magical Doremi #
# (MasterVisualList at $70000,
# the compressed graphics, palettes and tilemaps are located here)
#
# Usage:
# this_script.py PICO_ROM.bin offset
#======================================================================

import sys
import os.path

#======================================================================
# -------------------------------------------------
# Main
# -------------------------------------------------

if len(sys.argv) == 1:
    print("Usage: input_file offset")
    exit()

if os.path.exists(sys.argv[1]) == False:
    print("Input file not found")
    exit()

MASTERNAME  = sys.argv[1][:-4]
offset      = int("0x"+sys.argv[2],16)
input_file  = open(sys.argv[1],"rb")
output_file = open(MASTERNAME+"_"+str(hex(offset)[2:].upper())+".bin","wb+")

# -------------------------------------------------

Looping = True
input_file.seek(offset)
while Looping:
    d0 = 0
    d0 = ord(input_file.read(1)) & 0xFF
    if (d0 & 0x80) == 0x80:
        d0 -= 0x7E
        d2 = 0
        d2 = ord(input_file.read(1)) & 0xFF
        d2 += 1
        a4 = output_file.tell()
        a6 = output_file.tell()
        a4 -= d2
        for i in range(0,d0+1):
            #print(hex(a4),hex(a6),hex(d0))
            output_file.seek(a4)
            gotbyt = ord(output_file.read(1)) & 0xFF
            output_file.seek(a6)
            output_file.write(bytes([gotbyt]))
            a4 += 1
            a6 += 1
        output_file.seek(a6)    # return output
    elif d0 != 0:
        for i in range(0,d0):
            gotbyt = ord(input_file.read(1)) & 0xFF
            output_file.write(bytes([gotbyt]))
    else:
        #print("End of Data")
        Looping = False

#ROM:00001DD6 PicoDecomp:                             ; CODE XREF: PicoVdp_PkDataComp+1Ap
#ROM:00001DD6                 movem.l d0-d7/a3-a4,-(sp)
#ROM:00001DDA
#ROM:00001DDA loc_0_1DDA:                             ; CODE XREF: PicoDecomp+18j
#ROM:00001DDA                                         ; PicoDecomp+30j
#ROM:00001DDA                 moveq   #0,d0
#ROM:00001DDC                 move.b  (a5)+,d0
#ROM:00001DDE                 bmi.w   loc_0_1DF0
#ROM:00001DE2                 beq.w   PicoDcmp_End
#ROM:00001DE6                 subq.l  #1,d0
#ROM:00001DE8
#ROM:00001DE8 loc_0_1DE8:                             ; CODE XREF: PicoDecomp+14j
#ROM:00001DE8                 move.b  (a5)+,(a6)+
#ROM:00001DEA                 dbf     d0,loc_0_1DE8
#ROM:00001DEE                 bra.s   loc_0_1DDA
#ROM:00001DF0 ; ---------------------------------------------------------------------------
#ROM:00001DF0
#ROM:00001DF0 loc_0_1DF0:                             ; CODE XREF: PicoDecomp+8j
#ROM:00001DF0                 subi.l  #$7E,d0 ; '~'
#ROM:00001DF6                 moveq   #0,d2
#ROM:00001DF8                 move.b  (a5)+,d2
#ROM:00001DFA                 addq.l  #1,d2
#ROM:00001DFC                 movea.l a6,a4
#ROM:00001DFE                 suba.l  d2,a4
#ROM:00001E00
#ROM:00001E00 loc_0_1E00:                             ; CODE XREF: PicoDecomp+2Cj
#ROM:00001E00                 move.b  (a4)+,(a6)+
#ROM:00001E02                 dbf     d0,loc_0_1E00
#ROM:00001E06                 bra.s   loc_0_1DDA
#ROM:00001E08 ; ---------------------------------------------------------------------------
#ROM:00001E08
#ROM:00001E08 PicoDcmp_End:                           ; CODE XREF: PicoDecomp+Cj
#ROM:00001E08                 movem.l (sp)+,d0-d7/a3-a4
#ROM:00001E0C                 rts

# ======================================================================

# ----------------------------
# End
# ----------------------------

print("Done.")
input_file.close()
output_file.close()