David,
Z80 - far too modern for me. I was using machine code in the 1960s!
Best regards,
Peter
mailto:[email protected]
www.ptoye.com
-------------------------
Tuesday, February 28, 2017, 8:18:55 PM, you wrote:
> Peter Toye <[email protected]> writes:
>> David and other,
>> All of which makes me think that it's not really worth while pursuing
>> this development any further. As an ex-programmer (yes, I sometimes
>> did write comments, but in assembler you rather have to)
> How else would you keep track of cycle counts?
> .Z80
> NAME ('SCROLL')
> ENTRY SCRLFT,SCRRIG
> PUBLIC SCRX
> EXT STAGE,SHBTAB
> EXT DELAY
> EXT SCREEN,OUTCTL
> DSEG
> SCRLFT: LD IY,STAGE ;14(20)
> LD HL,SCRX ;30
> LD A,4 ;37
> ADD A,(HL) ;44
> LD (HL),A ;51
> ADD A,44 ;58
> LD L,A ;62
> LD H,0 ;69
> LD E,L ;73
> LD D,H ;77
> ADD HL,HL ;88
> ADD HL,DE ;99
> EX DE,HL ;103
> ADD IY,DE ;118
> LD A,12 ;125
> LD (SPSAVE),SP ;145
> LD SP,SCREEN+22 ;155
> SCRL05: EX AF,AF' ;4
> LD A,(IY) ;23
> AND 31 ;30
> ADD A,A ;34
> LD C,A ;38
> LD B,0 ;45
> LD HL,SHBTAB ;55
> ADD HL,BC ;66
> LD E,(HL) ;73
> INC HL ;79
> LD D,(HL) ;86
> LD C,4 ;93
> SCRL10: LD A,70H ;7
> OR C ;11
> DEFW OUTCTL ;22
> LD B,16 ;29
> SCRL11: EX DE,HL ;4
> LD E,(HL) ;11
> INC HL ;17
> LD D,(HL) ;24
> INC HL ;30
> EX DE,HL ;34
> REPT 11
> EX (SP),HL ;35
> DEC SP ;41
> DEC SP ;47
> ENDM ;551
> EX (SP),HL ;586
> LD HL,22+40H ;596
> ADD HL,SP ;607
> LD SP,HL ;611
> DJNZ SCRL11 ;10008
> SRL C ;10016
> JR C,SCRL20 ;10023 / 30237
> LD HL,-16*40H ;10033
> ADD HL,SP ;10044
> LD SP,HL ;10048
> JP SCRL10 ;10058
> SCRL20: LD A,70H
> DEFW OUTCTL
> EX AF,AF' ;30241
> DEC A ;30245
> INC IY ;30255
> JP NZ,SCRL05 ;363335
> SCRL21: LD SP,(SPSAVE) ;363373
> LD A,182
> JP DELAY
> Though I have to admit that this was from my youth, an age where you
> consider yourself and your memory immortal.
> DELAY is sort of a misnomer: it does not actually do any delay but
> tells the timing logic how much time a routine spent doing its job.
> Since we are talking about 363373 cycles on a 4MHz machine, the unit for
> "DELAY" would appear to be slices of 0.5ms.
> Scrolling by 16 pixels on a bitmapped display by using
> EX (SP),HL ;19
> DEC SP ;25
> DEC SP ;31
> as the workhorse rather than
> LDI ;16
> LDI ;32
> may seem a bit overoptimizing but it leaves quite more registers
> available for loop control and stride adjustment and only takes 3 bytes
> instead of 4.
> Sorry for the distraction: your remark about the necessity of commenting
> assembly language triggered this memory.
> It turns out that basically the module moving player and monsters
> actually has bonafide comments in it (and it is not timing-critical so
> there are no cycle counts and no call of DELAY). A collaborator
> insisted on them._______________________________________________
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