Difference between revisions of "Z80 Routines:Graphic:largesprite"

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[[Category:Z80 Routines:Graphic|largesprite]][[Category:Z80 Routines|largesprite]]
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#REDIRECT [[Z80_Routines:Graphic:putLargeSprite]]
The '''Largesprite''' routine is used to copy the content of a sprite to the Graph Buffer. The sprite can be of any size (max. 96x64), so the input of the largesprite routine is quite big.
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Here is Joe Wingbermuehle's version, which is the one used in ION.
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<nowiki>
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;=======================
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;LargeSprite
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;by Joe Wingbermuehle
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;=======================
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;Does:  Copy a sprite to the gbuf
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;Input:  ix=sprite address, a='x', l='y', b='height' (in pixels), c='width' (in bytes, e.g. 2 would be 16)
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;Output: The sprite is copied to the gbuf
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;-----------------------
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largeSprite:
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  di                                ;turn interrupts off (we want to use shadow registers)
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  ex  af,af'
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                                      ;exchange af with af'    \
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  ld  a,c                          ;ld c in a (a = 'width')  | for not destroying a ('x')
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  push  af                          ;push a                  |
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      ex  af,af'
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                                      ;exchange back            | and 'width' is now in a' (saved)
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      ld  e,l                        ;e = 'y'
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      ld  h,$00                      ;h =  0
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      ld  d,h                        ;d =  0
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      add  hl,de                    ;'y' *2  \
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      add  hl,de                    ;    *3  | calculate 'y' *12 because 'y' is 'in rows'
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      add  hl,hl                    ;    *6  |  (screen is 12 bytes in length)
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      add  hl,hl                    ;    *12 /
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      ld  e,a                        ;e = 'x'
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      and  $07                      ;and %00000111
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      ld  c,a                        ;last 3 bits in c (amount of bits to shift all bytes)
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      srl  e                        ;e/2  | shifting e ('x') 3 bits to the right
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      srl  e                        ; /4  |  %11111111 becomes %00011111 for example
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      srl  e                        ; /8  /
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      add  hl,de                    ;hl = 'y'; de = 'x' (rounded) | add them
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      ld  de, gbuf                  ;de = the adress of graph buffer
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      add  hl,de                    ;add hl to the adress of the gbuf
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largeSpriteLoop1:
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      push  hl                      ;save adress
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largeSpriteLoop2:
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        ld  d,(ix)                  ;first sprite data in d
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        ld  e,$00                  ;e = 0
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        ld  a,c                    ;a = c (to not destroy c)
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        or  a                      ;is a = 0? (same as cp 0)
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        jr  z,largeSpriteSkip1      ;if theres nothing to shift (a = 0) loop it
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largeSpriteLoop3:
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        srl  d                      ;shift one bit to the right; put the destroyed bit in the carry flag
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        rr  e                      ;put the carry flag in e (%00000000 becomes %10000000 if carry flag = 1)
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        dec  a                      ;decrease counter (with was 'the amount of bits to shift')
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        jr  nz,largeSpriteLoop3    ;if the counter is not 0 loop back
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largeSpriteSkip1:
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        ld  a,(hl)                  ;graphbyte in a
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        xor  d                      ;xor first byte of sprite (that can be changed to 'or d' if you want a OR-routine)
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        ld  (hl),a                  ;back to buffer
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        inc  hl                    ;increase pointer
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        ld  a,(hl)                  ;graphbyte in a
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        xor  e                      ;xor with shifted sprite byte (change to 'or e' for OR-routine)
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        ld  (hl),a                  ;back to buffer
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        inc  ix                    ;increase sprite adress
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        ex  af,af'
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                                      ;exchange af with af' ( a is now the 'width' from the first line)
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        dec  a                      ;decrease 'width'
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        push  af                    ;push the 'width'
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            ex  af,af'
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                                      ;exchange back
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        pop  af                    ;pop the 'width'
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        jr  nz,largeSpriteLoop2    ;if a is not 0 (if a = 0 then we would be done) loop it
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      pop  hl                        ;pop gbuf adress (search the last push hl!)
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  pop  af                          ;pop  | to restore the real 'width'
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  push  af                          ;push /
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      ex  af,af'
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                                      ;af' must be the original 'width' when loop 'largeSpriteLoop1'
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      ld  de,$0C                    ;ld de,12
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      add  hl,de                    ;next line
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      djnz  largeSpriteLoop1        ;if not b = 0 loop (b = height of sprite)
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  pop  af                          ;pop because we dont want a stack problem :)
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  ret                                ;return</nowiki>
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===Example===
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-----
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<nowiki>
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  ;...
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  ld  a,8  ;y
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  ld  l,a
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  ld  a,16  ;x
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  ld  b,8  ;height
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  ld  c,2  ;width in bytes
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  ld  ix,sprite
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  call largesprite
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  call fastcopy
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  ;...
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sprite:
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  .db %11111111,%11111111
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  .db %10000000,%00000001
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  .db %10000000,%00000001
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  .db %10000000,%00000001
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  .db %10000000,%00000001
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  .db %10000000,%00000001
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  .db %10000000,%00000001
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  .db %11111111,%11111111</nowiki>
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===Macro===
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-----
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This macro can be used with Tasm or Spasm.
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#define lsprite(lsprite_down,lsprite_right,lsprite_size_down,lsprite_size_right,lsprite_address) ld a,lsprite_down \ ld l,a \ ld a,lsprite_right \ ld b,lsprite_size_down \ ld c,lsprite_size_right \ ld ix,lsprite_address \ call largesprite
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'''[→How do you do a line break in this Wiki?]'''
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The above example would be:
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<nowiki>
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  ;...
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  lsprite(16, 8, 8, 2,sprite)
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  call fastcopy
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  ;...
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sprite:
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  .db %11111111,%11111111
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  .db %10000000,%00000001
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  .db %10000000,%00000001
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  .db %10000000,%00000001
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  .db %10000000,%00000001
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  .db %10000000,%00000001
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  .db %10000000,%00000001
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  .db %11111111,%11111111</nowiki>
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===Differences between the 83+ and the 83 in Largesprite===
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You need to define 'gbuf' which is [[83Plus:RAM:9340|$9340]] on the Ti83+ and [[83:RAM:8E29|$8E29]] on the Ti83 before you include the largesprite routine.
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<nowiki>
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#ifdef TI83P
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#define gbuf $9340
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#else
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#define gbuf $8E29
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#endif</nowiki>
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Latest revision as of 01:13, 25 June 2010