163 lines
5.7 KiB
Python
163 lines
5.7 KiB
Python
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#-----------------------------------------------------------------------
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#
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# Loader-specific SYS extensions
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#
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#-----------------------------------------------------------------------
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from asm import *
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# Peek into the ROM's symbol table
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videoY = symbol('videoY')
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sysArgs = symbol('sysArgs0')
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vPC = symbol('vPC')
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vLR = symbol('vLR')
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channelMask = symbol('channelMask_v4')
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#-----------------------------------------------------------------------
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# Extension SYS_LoaderNextByteIn_32
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#-----------------------------------------------------------------------
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# sysArgs[0:1] Current address
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# sysArgs[2] Checksum
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# sysArgs[3] Wait value (videoY)
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label('SYS_LoaderNextByteIn_32')
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ld([videoY]) #15
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xora([sysArgs+3]) #16
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bne('.sysNbi#19') #17
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ld([sysArgs+0],X) #18
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ld([sysArgs+1],Y) #19
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ld(IN) #20
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st([Y,X]) #21
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adda([sysArgs+2]) #22
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st([sysArgs+2]) #23
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ld([sysArgs+0]) #24
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adda(1) #25
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st([sysArgs+0]) #26
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ld(hi('REENTER'),Y) #27
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jmp(Y,'REENTER') #28
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ld(-32/2) #29
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# Restart the instruction in the next timeslice
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label('.sysNbi#19')
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ld([vPC]) #19
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suba(2) #20
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st([vPC]) #21
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ld(-28/2) #22
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ld(hi('REENTER'),Y) #23
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jmp(Y,'REENTER') #24
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nop() #25
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#-----------------------------------------------------------------------
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# Extension SYS_LoaderProcessInput_64
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#-----------------------------------------------------------------------
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# sysArgs[0:1] Source address
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# sysArgs[2] Checksum
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# sysArgs[4] Copy count
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# sysArgs[5:6] Destination address
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label('SYS_LoaderProcessInput_64')
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ld([sysArgs+1],Y) #15
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ld([sysArgs+2]) #16
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bne('.sysPi#19') #17
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ld([sysArgs+0]) #18
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suba(65, X) #19 Point at first byte of buffer
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ld([Y,X]) #20 Command byte
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st([Y,Xpp]) #21 X++
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xora(ord('L')) #22 This loader lumps everything under 'L'
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bne('.sysPi#25') #23
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ld([Y,X]); C('Valid command')#24 Length byte
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st([Y,Xpp]) #25 X++
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anda(63) #26 Bit 6:7 are garbage
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st([sysArgs+4]) #27 Copy count
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ld([Y,X]) #28 Low copy address
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st([Y,Xpp]) #29 X++
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st([sysArgs+5]) #30
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ld([Y,X]) #31 High copy address
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st([Y,Xpp]) #32 X++
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st([sysArgs+6]) #33
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ld([sysArgs+4]) #34
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bne('.sysPi#37') #35
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# Execute code (don't care about checksum anymore)
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ld([sysArgs+5]); C('Execute')#36 Low run address
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st([vLR]) #37 https://forum.gigatron.io/viewtopic.php?p=29#p29
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suba(2) #38
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st([vPC]) #39
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ld([sysArgs+6]) #40 High run address
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st([vPC+1]) #41
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st([vLR+1]) #42
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ld(0); C('Reactivate sound channels?')#43
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ld(2,Y) #44
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ora([Y,254]) #45
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ora([Y,255]) #46
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ld(3,Y) #47
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ora([Y,254]) #48
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ora([Y,255]) #49
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ld(4,Y) #50
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ora([Y,254]) #51
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ora([Y,255]) #52
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bne(pc()+3) #53
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bra(pc()+3) #54
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ld(3); C('Yes')#55
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ld(0); C('No')#56
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ora([channelMask]) #57
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st([channelMask]) #58
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ld(hi('REENTER'),Y) #59
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jmp(Y,'REENTER') #60
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ld(-64/2) #61
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# Invalid checksum
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label('.sysPi#19')
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wait(25-19); C('Invalid checksum')#19 Reset checksum
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# Unknown command
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label('.sysPi#25')
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ld(ord('g')); C('Unknown command')#25 Reset checksum
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st([sysArgs+2]) #26
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ld(hi('REENTER'),Y) #27
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jmp(Y,'REENTER') #28
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ld(-32/2) #29
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# Loading data
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label('.sysPi#37')
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ld([sysArgs+0]); C('Loading data')#37 Continue checksum
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suba(1, X) #38 Point at last byte
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ld([Y,X]) #39
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st([sysArgs+2]) #40
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ld(hi('REENTER'),Y) #41
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jmp(Y,'REENTER') #42
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ld(-46/2) #43
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#-----------------------------------------------------------------------
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# Extension SYS_LoaderPayloadCopy_34
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#-----------------------------------------------------------------------
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# sysArgs[0:1] Source address
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# sysArgs[4] Copy count
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# sysArgs[5:6] Destination address
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label('SYS_LoaderPayloadCopy_34')
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ld([sysArgs+4]) #15 Copy count
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beq('.sysCc#18') #16
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suba(1) #17
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st([sysArgs+4]) #18
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ld([sysArgs+0],X) #19 Current pointer
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ld([sysArgs+1],Y) #20
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ld([Y,X]) #21
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ld([sysArgs+5],X) #22 Target pointer
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ld([sysArgs+6],Y) #23
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st([Y,X]) #24
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ld([sysArgs+5]) #25 Increment target
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adda(1) #26
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st([sysArgs+5]) #27
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bra('.sysCc#30') #28
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label('.sysCc#18')
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ld(hi('REENTER'),Y) #18,29
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wait(30-19) #19
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label('.sysCc#30')
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jmp(Y,'REENTER') #30
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ld(-34/2) #31
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#-----------------------------------------------------------------------
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#
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#-----------------------------------------------------------------------
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