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Optimize graphx circle #744

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Optimize graphx circle #744

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ed58edb
optimized compare in circle routines
ZERICO2005 Sep 12, 2025
48c2796
use add hl, hl to extract signbit into C
ZERICO2005 Mar 9, 2026
b0c99ff
optimized loop condition in circle routines
ZERICO2005 Mar 9, 2026
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79 changes: 36 additions & 43 deletions src/graphx/graphx.asm
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Original file line number Diff line number Diff line change
Expand Up @@ -1645,40 +1645,39 @@ _Circle:
inc bc
ld (iy - 3), bc
ld bc, (iy - 9)
or a, a

sbc hl, hl
sbc hl, bc
jp m, .cmp0
jp pe, .cmp1
jr .cmp2
.cmp0:
jp po, .cmp1
.cmp2:
adc hl, bc ; set Z/NZ
add hl, hl ; C = sign
ld hl, (iy - 3)
jr z, .cmp2 ; BC == 0
jr nc, .cmp1 ; BC > 0
.cmp2: ; BC <= 0
add hl, hl
inc hl
add hl, bc
jr .next
.cmp1:
jr .loop
.cmp1: ; BC > 0
ld bc, (iy - 6)
dec bc
ld (iy - 6), bc
ld hl, (iy - 3)
or a, a
sbc hl, bc
add hl, hl
inc hl
ld de, (iy - 9)
add hl, de
.next:
.loop:
ld (iy - 9), hl
ld bc, (iy - 3)
ld hl, (iy - 6)
or a, a
sbc hl, bc
jp p, .check
add hl, hl ; C = sign
jr nc, .check ; positive
jp pe, .sectors
jr .exit
; jr .exit
xor a, a ; sets PE
.check:
jp po, .sectors
.exit:
Expand Down Expand Up @@ -1706,7 +1705,7 @@ gfx_Circle:
inc hl
sbc hl, bc ; HL = 1 - BC
call gfx_Wait
jr _Circle.next
jr _Circle.loop

;-------------------------------------------------------------------------------
_FillCircle:
Expand Down Expand Up @@ -1772,43 +1771,40 @@ _FillCircle:
ld bc, (ix - 3)
inc bc
ld (ix - 3), bc
ld bc, (ix - 9)
or a, a
ld bc, (hl) ; ld bc, (ix - 9)

sbc hl, hl
sbc hl, bc
jp m, .cmp0
jp pe, .cmp2
jr .cmp1
.cmp0:
jp po, .cmp2
.cmp1:
adc hl, bc ; set Z/NZ
add hl, hl ; C = sign
ld hl, (ix - 3)
jr z, .cmp2 ; BC == 0
jr nc, .cmp1 ; BC > 0
.cmp2: ; BC <= 0
add hl, hl
inc hl
add hl, bc
jr .cmp3
.cmp2:
jr .loop
.cmp1: ; BC > 0
ld bc, (ix - 6)
dec bc
ld (ix - 6), bc
ld hl, (ix - 3)
ld de, (ix - 9)
or a, a
sbc hl, bc
add hl, hl
inc hl
add hl, de
.cmp3:
.loop:
ld (ix - 9), hl
ld bc, (ix - 3)
ld hl, (ix - 6)
or a, a
sbc hl, bc
jp p, .check
add hl, hl ; C = sign
jr nc, .check ; positive
jp pe, .fillsectors
ld sp, ix
pop ix
ret
; jr .ResetStack
xor a, a ; sets PE
.check:
jp po, .fillsectors
.ResetStack:
Expand Down Expand Up @@ -1837,7 +1833,7 @@ gfx_FillCircle:
ld (ix - 3), hl
inc hl
sbc hl, bc ; HL = 1 - BC
jr _FillCircle.cmp3
jr _FillCircle.loop

;-------------------------------------------------------------------------------
_FillCircle_NoClip:
Expand Down Expand Up @@ -1898,25 +1894,22 @@ _FillCircle_NoClip:
inc bc
ld (ix - 3), bc
ld bc, (ix - 9)
or a, a

sbc hl, hl
sbc hl, bc
jp m, .cmp0
jp pe, .cmp2
jr .cmp1
.cmp0:
jp po, .cmp2
.cmp1:
adc hl, bc ; set Z/NZ
add hl, hl ; C = sign
ld hl, (ix - 3)
jr z, .cmp2 ; BC == 0
jr nc, .cmp1 ; BC > 0
.cmp2: ; BC <= 0
add hl, hl
inc hl
add hl, bc
jr .loop
.cmp2:
.cmp1: ; BC > 0
ld bc, (ix - 6)
dec bc
ld (ix - 6), bc
ld hl, (ix - 3)
or a, a
sbc hl, bc
add hl, hl
Expand Down
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