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general graphx optimizations #742

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bca2a34
optimized the SMC used for gfx_floodfill. Saves 6 bytes
ZERICO2005 Sep 11, 2025
7e5163b
optimized floodfill while(x <= x2)
ZERICO2005 Mar 9, 2026
de9059e
optimized offscreen sprite clipping
ZERICO2005 Sep 12, 2025
142adb7
saved a relocation by switching _indcallHL to ti._indcall
ZERICO2005 Mar 7, 2026
b074a2f
optimized gfx_SetCharData
ZERICO2005 Mar 7, 2026
9094f1e
remove IX from gfx_TilePtr
ZERICO2005 Mar 9, 2026
33c99ef
use the power of djnz
ZERICO2005 Mar 9, 2026
de9c607
clear IYU trick
ZERICO2005 Mar 10, 2026
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128 changes: 66 additions & 62 deletions src/graphx/graphx.asm
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Original file line number Diff line number Diff line change
Expand Up @@ -381,13 +381,13 @@ gfx_AllocSprite:
add hl, bc
ld d, (hl) ; d = height
add hl, bc
ld hl, (hl) ; hl = malloc
ld iy, (hl) ; iy = malloc
push de
mlt de ; de = width * height
inc de ; +2 to store width and height
inc de ; de = width * height + 2
push de
call _indcallHL ; hl = malloc(width * height + 2)
call ti._indcall ; hl = malloc(width * height + 2)
pop de
pop de ; e = width, d = height, ude = unknown
; check if malloc failed (hl == 0)
Expand Down Expand Up @@ -2698,8 +2698,8 @@ gfx_TransparentSprite:
; Returns:
; None
push ix ; save ix sp
; returns directly to the caller of gfx_(Transparent)Sprite when offscreen
call _ClipCoordinates
jr nc, .culled
; iyl = new width (next)
; iyh = new height
ld (.amount), a
Expand All @@ -2718,7 +2718,6 @@ smcByte _TransparentColor
add ix, de
dec iyh
jr nz, .loop
.culled:
pop ix
ret

Expand Down Expand Up @@ -2779,8 +2778,8 @@ gfx_Sprite:
; Returns:
; None
push ix ; save ix sp
; returns directly to the caller of gfx_(Transparent)Sprite when offscreen
call _ClipCoordinates
jr nc, .culled
; iyl = new width (next)
; iyh = new height
wait_quick
Expand All @@ -2794,7 +2793,6 @@ gfx_Sprite:
add hl, bc ; move to next line
dec iyh
jr nz, .loop
.culled:
pop ix ; restore ix sp
ret

Expand Down Expand Up @@ -2941,25 +2939,30 @@ smcByte _TransparentColor
add ix, de
dec iyh ; loop for height
jr nz, .loop
_ClipCoordinates_Restore_IX:
pop ix ; restore stack pointer
ret

;-------------------------------------------------------------------------------
_ClipCoordinates_Offscreen:
; return directly to the caller of gfx_(Transparent)Sprite
pop hl ; return address for gfx_(Transparent)Sprite
jr _ClipCoordinates_Restore_IX
_ClipCoordinates:
; Clipping stuff
; Arguments:
; arg0 : Pointer to sprite structure
; arg1 : X coordinate
; arg2 : Y coordinate
; Returns:
; Offscreen: returns directly to the caller of gfx_(Transparent)Sprite
; A : How much to add to the sprite per iteration
; BCU: 0
; B : 0
; IYH: New sprite height
; IYL: New sprite width
; HL : Sprite pixel pointer
; IX : Buffer pixel pointer
; NC : If offscreen
ld ix, 6 ; get pointer to arguments
add ix, sp
ld hl, (ix + 3) ; hl -> sprite data
Expand Down Expand Up @@ -2995,7 +2998,7 @@ smcByte _YSpan
sub a, l ; a = negated relative y
.cliptop:
add hl, bc ; is partially clipped top?
ret nc
jr nc, _ClipCoordinates_Offscreen
ex de, hl ; e = new height - 1
ld c, a ; c = negated relative y
ld b, iyl ; b = width
Expand Down Expand Up @@ -3040,7 +3043,7 @@ smcWord _XSpan
sub a, l ; a = negated relative x
.clipleft:
add hl, bc ; is partially clipped left?
ret nc ; return if offscreen
jr nc, _ClipCoordinates_Offscreen
ex de, hl ; e = new width - 1
ld c, a ; bc = negated relative x
ld hl, (ix + 3) ; hl -> sprite data
Expand Down Expand Up @@ -3068,7 +3071,6 @@ smcWord _XMin
inc hl
ld ix, (CurrentBuffer)
add ix, de
scf ; set carry for success
ret

;-------------------------------------------------------------------------------
Expand Down Expand Up @@ -3141,24 +3143,24 @@ _Tilemap:
ld (.tilemethod), hl
push ix
ld ix, 0
lea bc, ix
inc.s bc ; clear UBC
add ix, sp
lea hl, ix - 12
ld sp, hl
ld iy, (ix + 6) ; iy -> tilemap structure

ld hl, (ix + y_offset)
ld c, (iy + t_tile_height)
ld a, (iy + t_type_height)
or a, a
jr nz, .heightpow2
ld b, (iy + t_type_height)
inc b
djnz .heightpow2
; UBC and B are zero
call ti._idvrmu
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@ZERICO2005 ZERICO2005 Mar 10, 2026

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by the way, couldn't this be changed to 16 bit division?

ex de, hl
push de
pop bc
jr .heightnotpow2
.heightpow2: ; compute as power of 2 height using shifts
ld b, a
dec c
ld a, l
and a, c
Expand All @@ -3173,16 +3175,16 @@ _Tilemap:

ld c, (iy + t_tile_width)
ld hl, (ix + x_offset) ; x offset
ld a, (iy + t_type_width)
or a, a
jr nz, .widthpow2
ld b, (iy + t_type_width)
inc b
djnz .widthpow2
; UBC and B are zero
call ti._idvrmu
ex de, hl
push de
pop bc
jr .widthnotpow2
.widthpow2:
ld b, a
dec c
ld a, l
and a, c
Expand Down Expand Up @@ -3293,41 +3295,43 @@ gfx_TilePtr:
; uint8_t *gfx_TilePtr(gfx_tilemap_t *tilemap, unsigned x_offset, unsigned y_offset) {
; return &tilemap->map[(x_offset/tilemap->tile_width)+((y_offset/tilemap->tile_height)*tilemap->width)];
; }
push ix
ld ix, 0
add ix, sp
ld iy, (ix + 6)
ld hl, (ix + 9)
ld a, (iy + t_type_width)
or a, a
jr nz, .fastdiv0
ld bc, 0
ld bc, 3
push bc
pop hl
add hl, sp
ld iy, (hl)
add hl, bc
ld hl, (hl)
ld b, (iy + t_type_width)
inc b
djnz .fastdiv0
; UBC and B are zero
ld c, (iy + t_tile_width)
call ti._idvrmu
ex de, hl
jr .widthnotpow2
.fastdiv0:
ld b, a
.div0:
srl h
rr l
djnz .div0
.widthnotpow2:
ex de, hl
ld hl, (ix + 12)
ld a, (iy + t_type_height)
or a, a
jr nz, .fastdiv1
ld bc, 0
.widthnotpow2:
ld hl, 9
add hl, sp
ld hl, (hl)
ld b, (iy + t_type_height)
inc b
djnz .fastdiv1
; UBC and B are zero
ld c, (iy + t_tile_height)
push de
call ti._idvrmu
ex de, hl
pop de
jr .heightnotpow2
.fastdiv1:
ld b, a
.div1: srl h
.div1:
srl h
rr l
djnz .div1
.heightnotpow2:
Expand All @@ -3336,7 +3340,6 @@ gfx_TilePtr:
add hl, de
ld de, (iy + t_data)
add hl, de
pop ix
ret

;-------------------------------------------------------------------------------
Expand Down Expand Up @@ -3398,11 +3401,6 @@ gfx_SetTextXY:
ld (_TextYPos), hl
push hl ; xpos=don't care, sp=&xpos
ex de, hl ; hl=return address
;-------------------------------------------------------------------------------
_indcallHL:
; Calls HL
; Inputs:
; HL : Address to call
jp (hl)

;-------------------------------------------------------------------------------
Expand Down Expand Up @@ -4004,13 +4002,17 @@ gfx_SetCharData:
; arg0 : Pointer to character data; if null returns current data
; Returns:
; Pointer to character data if null, otherwise pointer to next character
ld iy, 0
add iy, sp
ld hl, 6
add hl, sp
ld de, (hl) ; de -> custom_character_data
dec hl
dec hl
dec hl
ld a, (hl)
sbc hl, hl ; ld hl, 0
ld de, (iy + 6) ; de -> custom_character_data
sbc hl, de ; sets z flag if NULL
add hl, de
ld l, (iy + 3) ; hl = index
ld l, a ; hl = index
add hl, hl
add hl, hl
add hl, hl
Expand Down Expand Up @@ -4823,7 +4825,7 @@ gfx_ScaleSprite:
call _UCDivA ; ca = du = (source_width*256)/target_width
pop hl ; hl->src_data
pop de ; de->tgt_data
ld iy, 0
inc.s iy ; clear IYU
ld iyl, a
ld ixh, c ; (.du) = bc:iyl, ixl = target_height

Expand Down Expand Up @@ -5708,16 +5710,17 @@ gfx_FloodFill:
ld bc, (ix + 6)
call _GetPixel ; ov = p(x, y);

ld (.oldcolor0), a
ld (.oldcolor1), a
ld (.oldcolor2), a
ld b, (ix + 12)
cp a, b ; return if same color
jq z, .return

ld a, b
ld (.newcolor0), a
ld (.newcolor1), a
ld iy, _FloodFill_smc_base
ld (iy + (.oldcolor0 - _FloodFill_smc_base)), a
ld (iy + (.oldcolor1 - _FloodFill_smc_base)), a
ld (.oldcolor2), a

ld (iy + (.newcolor0 - _FloodFill_smc_base)), b
ld (iy + (.newcolor1 - _FloodFill_smc_base)), b

lea iy, ix
ld bc, -3224
Expand Down Expand Up @@ -5847,6 +5850,8 @@ smcWord _XMaxMinus1
.oldcolor1 = $-1
jr z, .forloop1

_FloodFill_smc_base := $

.ovat:
ld (ix + 6), bc
lea de, ix - 24 ; push(y, l, x-1, dy);
Expand Down Expand Up @@ -5914,26 +5919,25 @@ smcByte _YSpan
add hl, de
ex de, hl ; de -> draw location
ld hl, (ix - 15)

; carry is cleared here
jr .whileloop

.forloop2:
inc bc
inc de
.whileloop:
or a, a
; or a, a
sbc hl, bc
add hl, bc
jr c, .done
ld a, (de)
cp a, 0
xor a, 0
.oldcolor2 = $-1
jr nz, .forloop2

.done:
; Z and NC
.done: ; <-- NZ and C
ld (ix + 6), bc
ld (ix - 11), bc ; l = x;
or a, a
sbc hl, bc
jp nc, .forloop1start ; } while ((unsigned)x<=x2);

ld hl, 0
Expand Down
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