simplify branch logic for circle draw
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hugova
parent
a1089ccd1c
commit
385ae9c9e6
3 changed files with 31 additions and 43 deletions
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@ -8,27 +8,25 @@
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t2 = $E1
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X_math = radius
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Y_math = $E2
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jmp_location_pointer_two = $E3 ;16-bit value (uses E4)
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jmp_location_pointer = $E5 ;16-bit value (uses E6)
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;; E8 - EA is used by pixel.inc
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byte_to_paint_qaa = byte_to_paint
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byte_to_paint_qcb = $EB
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byte_to_paint_qca = $EC
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byte_to_paint_qdb = $ED
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byte_to_paint_qcb = $E3
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byte_to_paint_qca = $E4
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byte_to_paint_qdb = $E5
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btp_mem_pos_qaa = btp_mem_pos
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btp_mem_pos_qcb = $D0 ; 16bit value (uses D1)
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btp_mem_pos_qdb = $D2 ; 16bit value (uses D3)
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btp_mem_pos_qda = $D4 ; 16bit value (uses D5)
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btp_mem_pos_qab = $D6 ; 16bit value (uses D7)
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btp_mem_pos_qca = $D8 ; 16bit value (uses D9)
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btp_mem_pos_qba = $DA ; 16bit value (uses DB)
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btp_mem_pos_qbb = $DC ; 16bit value (uses DD)
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btp_mem_pos_qcb = $E6 ; 16bit value (uses E7)
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btp_mem_pos_qdb = $EB ; 16bit value (uses EC)
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btp_mem_pos_qda = $ED ; 16bit value (uses EE)
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btp_mem_pos_qab = $D0 ; 16bit value (uses D1)
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btp_mem_pos_qca = $D2 ; 16bit value (uses D3)
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btp_mem_pos_qba = $D4 ; 16bit value (uses D5)
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btp_mem_pos_qbb = $D6 ; 16bit value (uses D7)
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Y_qda = $DE
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Y_qdb = $DF
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Y_qbb = $E7 ;; <-- we use E7 here!
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Y_qaa = $C0
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Y_qda = $EF
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Y_qdb = $D8
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Y_qbb = $D9
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Y_qaa = $DA
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;;Reuse addresses, be carful here!
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temp__ = Y_qaa
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temp_ = Y_qda
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@ -24,16 +24,6 @@
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.proc circle; user-procedure :clobbers (A X Y) :clobbers-arguments 3
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.include "circle.inc"
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;; Because loop is so big, We need to save positions in pointer
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LDA #<while_x_bigger_then_y
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STA jmp_location_pointer
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LDA #>while_x_bigger_then_y
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STA jmp_location_pointer + 1
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LDA #<endif
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STA jmp_location_pointer_two
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LDA #>endif
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STA jmp_location_pointer_two + 1
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;; X_math = radius (share the same address)
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;;Y_math =0
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@ -140,7 +130,7 @@ while_x_bigger_then_y: ; C=1 here because above and branching logic
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draw_pixels:
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draw_qaa:
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LDY Y_qaa
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LDA byte_to_paint ;A byte containing a single 1. Coresponds to 2^rest(X_pos/8)
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LDA byte_to_paint_qaa ;A byte containing a single 1. Coresponds to 2^rest(X_pos/8)
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ORA (btp_mem_pos), Y; Y = rest(Y_pos/8)
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STA (btp_mem_pos), Y
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draw_qba:
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@ -149,7 +139,7 @@ draw_qba:
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STA (btp_mem_pos_qba), Y
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draw_qda:
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LDY Y_qda
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LDA byte_to_paint
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LDA byte_to_paint_qaa
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ORA (btp_mem_pos_qda), Y
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STA (btp_mem_pos_qda), Y
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draw_qca:
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@ -188,10 +178,10 @@ qaa_y:
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BPL qaa_y_end
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qaa_y_underflow:
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;; Switch to chunk bellow
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; So we subtract #$0140
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;; So we subtract #$0140
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;; Note that C =1, read from while_x_bigger_then_y label.
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Sub_16 btp_mem_pos, btp_mem_pos + 1, #$40, #$01, ! ;-320
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Sub_16 btp_mem_pos_qba, btp_mem_pos_qba + 1, #$40, #$01,!
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Sub_16 btp_mem_pos_qaa, btp_mem_pos_qaa + 1, #$40, #$01, ! ;-320
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Sub_16 btp_mem_pos_qba, btp_mem_pos_qba + 1, #$40, #$01, ! ;-320
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STY Y_qaa ; Y_qaa =$07
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qaa_y_end:
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qda_y:
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@ -235,7 +225,7 @@ qcb_x_end:
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;; if t2 < 0 then skip to endif
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;; we can skipp CMP #$00 because SBC above do the same
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BPL if
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JMP (jmp_location_pointer_two) ; jump to endif
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JMP endif
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if:
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change_x:
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DEC X_math
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@ -244,8 +234,8 @@ qaa_x:
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ASL byte_to_paint
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BCC qaa_x_end
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qaa_x_overflow:
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Sub_16 btp_mem_pos_qaa, btp_mem_pos_qaa + 1, #$08, #$00, ! ;+8
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Sub_16 btp_mem_pos_qda, btp_mem_pos_qda + 1, #$08, #$00, ! ;+8
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Sub_16 btp_mem_pos_qaa, btp_mem_pos_qaa + 1, #$08, #$00, ! ;-8
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Sub_16 btp_mem_pos_qda, btp_mem_pos_qda + 1, #$08, #$00, ! ;-8
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;; Restores byte to paint
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INC byte_to_paint
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qaa_x_end:
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@ -255,16 +245,16 @@ qca_x:
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BCC qca_x_end
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qca_x_overflow:
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ROR byte_to_paint_qca
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Add_16 btp_mem_pos_qca, btp_mem_pos_qca + 1, #$08, #$00, !
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Add_16 btp_mem_pos_qba, btp_mem_pos_qba + 1, #$08, #$00, !
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Add_16 btp_mem_pos_qca, btp_mem_pos_qca + 1, #$08, #$00, ! ;+8
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Add_16 btp_mem_pos_qba, btp_mem_pos_qba + 1, #$08, #$00, ! ;+8
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qca_x_end:
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qdb_y:
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DEC Y_qdb
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BPL qdb_y_end
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qdb_overflow:
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Sub_16 btp_mem_pos_qdb, btp_mem_pos_qdb + 1, #$3f, #$01, ! ;+320
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Sub_16 btp_mem_pos_qcb, btp_mem_pos_qcb + 1, #$40, #$01, ! ;+320
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Sub_16 btp_mem_pos_qdb, btp_mem_pos_qdb + 1, #$3f, #$01, ! ;-320
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Sub_16 btp_mem_pos_qcb, btp_mem_pos_qcb + 1, #$40, #$01, ! ;-320
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STY Y_qdb
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qdb_y_end:
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@ -285,7 +275,7 @@ endif:
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LDA X_math
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CMP Y_math
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BCC end
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JMP (jmp_location_pointer)
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jmp while_x_bigger_then_y
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end:
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RTS
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.endproc
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@ -10,8 +10,8 @@
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;.include "routines/arithmatic/mult_test.s"
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;.include "routines/arithmatic/div_test.s"
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.include "routines/circle/circle_test.s"
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;.include "routines/circle/circle_test_size.s"
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;.include "routines/circle/circle_test.s"
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.include "routines/circle/circle_test_size.s"
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;.include "routines/circle/circle_test_position.s"
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;.include "routines/line/line_test.s"
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;.include "routines/text/char_draw_test.s"
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