mirror of
https://github.com/lscharen/iigs-game-engine.git
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Break up large source code files to help with dependency ordering
This commit is contained in:
Lucas Scharenbroich
parent
76180b6feb
commit
29d70dc567
88
src/Math.s
Normal file
88
src/Math.s
Normal file
@ -0,0 +1,88 @@
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; Math-y functions
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mx %00
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; Special subroutine to divide the accumulator by 164 and return remainder in the Accumulator
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;
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; 164 = $A4 = 1010_0100
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Mod164 cmp #%1010010000000000
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bcc *+5
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sbc #%1010010000000000
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cmp #%0101001000000000
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bcc *+5
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sbc #%0101001000000000
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cmp #%0010100100000000
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bcc *+5
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sbc #%0010100100000000
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cmp #%0001010010000000
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bcc *+5
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sbc #%0001010010000000
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cmp #%0000101001000000
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bcc *+5
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sbc #%0000101001000000
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cmp #%0000010100100000
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bcc *+5
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sbc #%0000010100100000
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cmp #%0000001010010000
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bcc *+5
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sbc #%0000001010010000
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cmp #%0000000101001000
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bcc *+5
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sbc #%0000000101001000
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cmp #%0000000010100100
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bcc *+5
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sbc #%0000000010100100
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rts
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; Special subroutine to divide the accumulator by 208 and return remainder in the Accumulator
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;
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; 208 = $D0 = 1101_0000
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;
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; There are probably faster hacks to divide a 16-bit unsigned value by 208
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; https://www.drdobbs.com/parallel/optimizing-integer-division-by-a-constan/184408499
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; https://embeddedgurus.com/stack-overflow/2009/06/division-of-integers-by-constants/
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Mod208 cmp #%1101000000000000
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bcc *+5
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sbc #%1101000000000000
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cmp #%0110100000000000
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bcc *+5
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sbc #%0110100000000000
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cmp #%0011010000000000
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bcc *+5
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sbc #%0011010000000000
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cmp #%0001101000000000
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bcc *+5
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sbc #%0001101000000000
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cmp #%0000110100000000
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bcc *+5
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sbc #%0000110100000000
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cmp #%0000011010000000
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bcc *+5
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sbc #%0000011010000000
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cmp #%0000001101000000
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bcc *+5
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sbc #%0000001101000000
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cmp #%0000000110100000
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bcc *+5
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sbc #%0000000110100000
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cmp #%0000000011010000
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bcc *+5
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sbc #%0000000011010000
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rts
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237
src/blitter/Rotation.s
Normal file
237
src/blitter/Rotation.s
Normal file
@ -0,0 +1,237 @@
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; Support rotating the BG1 graphics by leveraging the fact that a rotation function can be decomposed
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; into an addition of two function parametertized by the angle of rotation: pixel = *(f(x, a) + f(y, a))
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;
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; The pre-build a number of rotation tables and then populate the direct page values and Y-register values
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; for each line of the blitter, such that a single lda (00),y instruction fetched the appropriate data
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;
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; This is about as fast of a rotation as we can do.
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;
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; When possible, off-screen locations are calculate to produce an address of $FFFE, so that the last two bytes
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; of the BG1 data buffer provides the "fill value".
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ANGLEBNK ext
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ApplyBG1XPosAngle ENT
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phb
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phk
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plb
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jsr _ApplyBG1XPosAngle
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plb
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rtl
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_ApplyBG1XPosAngle
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; phy
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; lda BG1StartX
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; jsr Mod164
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; sta BG1StartXMod164
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; lda #162
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; sec
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; sbc StartXMod164
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; bpl *+6
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; clc
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; adc #164
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; clc
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; adc BG1StartXMod164
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; cmp #164
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; bcc *+5
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; sbc #164
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; clc
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; adc 1,s
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; tay ; cache the value
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; pla ; pop the value
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phd ; save the direct page because we are going to switch to the
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lda BlitterDP ; blitter direct page space and fill in the addresses
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tcd
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lda #^ANGLEBNK
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sta $fe
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sty $fc ; Store in the new direct page
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ldy #162
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tyx
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:loop
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lda [$fc],y
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sta 00,x ; store the value
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dey
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dey
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dex
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dex
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bpl :loop
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pld
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rts
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ApplyBG1YPosAngle ENT
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phb
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phk
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plb
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jsr _ApplyBG1YPosAngle
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plb
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rtl
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_ApplyBG1YPosAngle
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:virt_line equ tmp0
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:lines_left equ tmp1
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:draw_count equ tmp2
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:ytbl_idx equ tmp3
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:angle_tbl equ tmp4
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sty :angle_tbl
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lda BG1StartY
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jsr Mod208
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sta BG1StartYMod208
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sta :ytbl_idx ; Start copying from the first entry in the table
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lda StartYMod208 ; This is the base line of the virtual screen
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sta :virt_line ; Keep track of it
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lda ScreenHeight
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sta :lines_left
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:loop
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lda :virt_line
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asl
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tax
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ldal BTableLow,x ; Get the address of the first code field line
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tay
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sep #$20
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ldal BTableHigh,x
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pha ; push the bank on the stack
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plb
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rep #$20
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lda :virt_line
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and #$000F
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eor #$FFFF
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inc
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clc
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adc #16
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min :lines_left
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sta :draw_count ; Do this many lines
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asl
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tax
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lda :ytbl_idx ; Read from this location (duplicate every 4 lines)
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lsr
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lsr
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asl
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clc
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adc :angle_tbl
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sec
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sbc #ANGLEBNK
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jsr CopyAngleYTableToBG1Addr ; or CopyBG1YTableToBG1Addr2
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lda :virt_line ; advance to the virtual line after the segment we just
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clc ; filled in
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adc :draw_count
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sta :virt_line
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lda :ytbl_idx ; advance the index into the YTable
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adc :draw_count
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sta :ytbl_idx
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lda :lines_left ; subtract the number of lines we just completed
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sec
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sbc :draw_count
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sta :lines_left
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jne :loop
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phk
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plb
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rts
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; Unrolled copy routine to move y_angle entries into BG1_ADDR position with an additional
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; shift. This has to be split into two
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;
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; A = index into the array (x2)
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; Y = starting line * $1000
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; X = number of lines (x2)
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CopyAngleYTableToBG1Addr
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phx
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phb
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phk ; restore access to this bank
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plb
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jsr SaveBG1AngleValues
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plb
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plx ; x is used directly in this routine
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jsr ApplyBG1OffsetValues
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rts
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SaveBG1AngleValues
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jmp (:tbl,x)
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:tbl da :none
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da :do01,:do02,:do03,:do04
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da :do05,:do06,:do07,:do08
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da :do09,:do10,:do11,:do12
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da :do13,:do14,:do15,:do16
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:do15 tax
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bra :x15
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:do14 tax
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bra :x14
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:do13 tax
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bra :x13
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:do12 tax
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bra :x12
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:do11 tax
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bra :x11
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:do10 tax
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bra :x10
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:do09 tax
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bra :x09
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:do08 tax
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bra :x08
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:do16 tax
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ldal ANGLEBNK+06,x
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sta BG1YCache+30
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:x15 ldal ANGLEBNK+06,x
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sta BG1YCache+28
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:x14 ldal ANGLEBNK+06,x
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sta BG1YCache+26
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:x13 ldal ANGLEBNK+06,x
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sta BG1YCache+24
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:x12 ldal ANGLEBNK+04,x
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sta BG1YCache+22
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:x11 ldal ANGLEBNK+04,x
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sta BG1YCache+20
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:x10 ldal ANGLEBNK+04,x
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sta BG1YCache+18
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:x09 ldal ANGLEBNK+04,x
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sta BG1YCache+16
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:x08 ldal ANGLEBNK+02,x
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sta BG1YCache+14
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:x07 ldal ANGLEBNK+02,x
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sta BG1YCache+12
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:x06 ldal ANGLEBNK+02,x
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sta BG1YCache+10
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:x05 ldal ANGLEBNK+02,x
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sta BG1YCache+08
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:x04 ldal ANGLEBNK+00,x
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sta BG1YCache+06
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:x03 ldal ANGLEBNK+00,x
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sta BG1YCache+04
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:x02 ldal ANGLEBNK+00,x
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sta BG1YCache+02
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:x01 ldal ANGLEBNK+00,x
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sta BG1YCache+00
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:none rts
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:do07 tax
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bra :x07
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:do06 tax
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bra :x06
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:do05 tax
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bra :x05
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:do04 tax
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bra :x04
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:do03 tax
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bra :x03
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:do02 tax
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bra :x02
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:do01 tax
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bra :x01
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320
src/blitter/TemplateUtils.s
Normal file
320
src/blitter/TemplateUtils.s
Normal file
@ -0,0 +1,320 @@
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; Untility function related to patching and manipulating the blitter template code
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mx %00
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; Generalized routine that calculates the on-screen address of the tiles and takes the
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; StartX and StartY values into consideration. This routine really exists to support
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; the dirty tile rendering mode and the tiles *must* be aligned with the playfield.
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; That is, StartX % 4 == 0 and StartY % 8 == 0. If these conditions are not met, then
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; screen will not render correctly.
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_RecalcTileScreenAddrs
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NextColPtr equ tmp0
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RowAddrPtr equ tmp1
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OnScreenAddr equ tmp2
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Counter equ tmp3
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jsr _OriginToTileStore ; Get the (col,row) of the tile in the upper-left corner of the playfield
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; Manually add the offsets to the NextCol and TileStoreYTable array address and put in a direct page
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; location so we can free up the registers.
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clc
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txa
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adc #NextCol
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sta NextColPtr
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tya
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adc #TileStoreYTable
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sta RowAddrPtr
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; Calculate the on-screen address of the upper-left corner of the playfiled
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lda ScreenY0 ; Calculate the address of the first byte
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asl ; of the right side of the playfield
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tax
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lda ScreenAddr,x ; This is the address for the left edge of the physical screen
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clc
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adc ScreenX0
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sta OnScreenAddr
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; Now, loop through the tile store
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lda #MAX_TILES
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sta Counter
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ldy #0
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:tsloop
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lda (NextColPtr),y ; Need to recalculate each time since the wrap-around could
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clc ; happen anywhere
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adc (RowAddrPtr) ;
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tax ; NOTE: Try to rework to use new TileStore2DLookup array
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lda OnScreenAddr
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stal TileStore+TS_SCREEN_ADDR,x
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clc
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adc #4 ; Go to the next tile
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iny
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iny
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cpy #2*41 ; If we've done 41 columns, move to the next line
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bcc :nohop
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inc RowAddrPtr ; Advance the row address (with wrap-around)
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inc RowAddrPtr
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ldy #0 ; Reset the column counter
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clc
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adc #{8*160}-{4*41}
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:nohop
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sta OnScreenAddr ; Save the updated on-screen address
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dec Counter
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bne :tsloop
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rts
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; Patch an 8-bit or 16-bit valueS into the bank. These are a set up unrolled loops to
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; quickly patch in a constanct value, or a value from an array into a given set of
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; templates.
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;
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; Because we have structured everything as parallel code blocks, most updates to the blitter
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; reduce to storing a constant value and have an amortized cost of just a single store.
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;
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; The utility of these routines is that they also handle setting just a range of lines
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; within a single bank.
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;
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; X = number of lines * 2, 0 to 32
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; Y = starting line * $1000
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; A = value
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;
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; Set M to 0 or 1
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SetConst ; Need a blank line here, otherwise the :tbl local variable resolveds backwards
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jmp (:tbl,x)
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:tbl da :bottom-00,:bottom-03,:bottom-06,:bottom-09
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da :bottom-12,:bottom-15,:bottom-18,:bottom-21
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da :bottom-24,:bottom-27,:bottom-30,:bottom-33
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da :bottom-36,:bottom-39,:bottom-42,:bottom-45
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da :bottom-48
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:top sta $F000,y
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sta $E000,y
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sta $D000,y
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sta $C000,y
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sta $B000,y
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sta $A000,y
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sta $9000,y
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sta $8000,y
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sta $7000,y
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sta $6000,y
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sta $5000,y
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sta $4000,y
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sta $3000,y
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sta $2000,y
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sta $1000,y
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sta: $0000,y
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:bottom rts
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; SetDPAddrs
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;
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; A = absolute address (largest)
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; Y = offset
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;
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; Initializes a bank of direct page offsets
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SetDPAddrs
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lda #$0800
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sta $F000,y
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lda #$0700
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sta $E000,y
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lda #$0600
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sta $D000,y
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lda #$0500
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sta $C000,y
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lda #$0400
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sta $B000,y
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lda #$0300
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sta $A000,y
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lda #$0200
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sta $9000,y
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lda #$0100
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sta: $8000,y
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lda #$0800
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sta $7000,y
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lda #$0700
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sta $6000,y
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lda #$0600
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sta $5000,y
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lda #$0500
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sta $4000,y
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lda #$0400
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sta $3000,y
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lda #$0300
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sta $2000,y
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lda #$0200
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sta $1000,y
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lda #$0100
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sta: $0000,y
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rts
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; SetAbsAddrs
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;
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; A = absolute address (largest)
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; Y = offset
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; X = number of lines
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;
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; Stores a value and decrements by $1000 for each line
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SetAbsAddrs sec
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jmp (:tbl,x)
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:tbl da :bottom-00,:bottom-03,:bottom-09,:bottom-15
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da :bottom-21,:bottom-27,:bottom-33,:bottom-39
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da :bottom-45,:bottom-51,:bottom-57,:bottom-63
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da :bottom-69,:bottom-75,:bottom-81,:bottom-87
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da :bottom-93
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:top sta $F000,y
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sbc #$1000
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sta $E000,y
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sbc #$1000
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sta $D000,y
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sbc #$1000
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sta $C000,y
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sbc #$1000
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sta $B000,y
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sbc #$1000
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sta $A000,y
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sbc #$1000
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sta $9000,y
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sbc #$1000
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sta $8000,y
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sbc #$1000
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sta $7000,y
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sbc #$1000
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sta $6000,y
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sbc #$1000
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sta $5000,y
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sbc #$1000
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sta $4000,y
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sbc #$1000
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sta $3000,y
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sbc #$1000
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sta $2000,y
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sbc #$1000
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sta $1000,y
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sbc #$1000
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sta: $0000,y
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:bottom rts
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; Fill up a full bank with blitter templates. Currently we can fit 16 lines per bank, so need
|
||||
; a total of 13 banks to hold the 208 lines for full-screen support
|
||||
;
|
||||
; A = high word of bank table
|
||||
; Y = index * 4 of the bank to initialize
|
||||
BuildBank
|
||||
|
||||
:bankArray equ tmp0
|
||||
:target equ tmp2
|
||||
:nextBank equ tmp4
|
||||
|
||||
stx :bankArray
|
||||
sta :bankArray+2
|
||||
|
||||
stz :target
|
||||
iny
|
||||
iny
|
||||
lda [:bankArray],y
|
||||
sta :target+2
|
||||
|
||||
iny ; move to the next item
|
||||
iny
|
||||
iny ; middle byte
|
||||
cpy #4*13 ; if greater than the array length, wrap back to zero
|
||||
bcc :ok
|
||||
ldy #1
|
||||
:ok lda [:bankArray],y ; Get the middle and high bytes of the address
|
||||
sta :nextBank
|
||||
|
||||
:next
|
||||
jsr :BuildLine2
|
||||
lda :target
|
||||
clc
|
||||
adc #$1000
|
||||
sta :target
|
||||
bcc :next
|
||||
|
||||
phb
|
||||
pei :target+1
|
||||
plb
|
||||
plb
|
||||
|
||||
; Change the patched value to one of DP_ENTRY, TWO_LYR_ENTRY or ONE_LYR_ENTRY based on the capabilities
|
||||
; that the engine needs.
|
||||
|
||||
lda #$F000+{DP_ENTRY} ; Set the address from each line to the next
|
||||
ldy #CODE_EXIT+1
|
||||
ldx #15*2
|
||||
jsr SetAbsAddrs
|
||||
|
||||
ldy #DP_ADDR
|
||||
jsr SetDPAddrs
|
||||
|
||||
ldy #$F000+CODE_EXIT ; Patch the last line with a JML to go to the next bank
|
||||
lda #{$005C+{DP_ENTRY}*256}
|
||||
sta [:target],y
|
||||
ldy #$F000+CODE_EXIT+2
|
||||
lda :nextBank
|
||||
sta [:target],y
|
||||
|
||||
ldy #$8000+CODE_EXIT ; Patch one line per bank to enable interrupts
|
||||
lda #{$004C+{ENABLE_INT}*256}
|
||||
sta [:target],y
|
||||
|
||||
plb
|
||||
rts
|
||||
|
||||
; This is the relocation subroutine, it is responsible for copying the template to a
|
||||
; memory location and patching up the necessary instructions.
|
||||
;
|
||||
; X = low word of address (must be a multiple of $1000)
|
||||
; A = high word of address (bank)
|
||||
:BuildLine
|
||||
stx :target
|
||||
sta :target+2
|
||||
|
||||
:BuildLine2
|
||||
lda #CODE_LEN ; round up to an even number of bytes
|
||||
inc
|
||||
and #$FFFE
|
||||
beq :nocopy
|
||||
dec
|
||||
dec
|
||||
tay
|
||||
:loop lda base,y
|
||||
sta [:target],y
|
||||
|
||||
dey
|
||||
dey
|
||||
bpl :loop
|
||||
|
||||
:nocopy lda #0 ; copy is complete, now patch up the addresses
|
||||
sep #$20
|
||||
|
||||
ldx #0
|
||||
lda :target+2 ; patch in the bank for the absolute long addressing mode
|
||||
:dobank ldy BankPatches,x
|
||||
sta [:target],y
|
||||
inx
|
||||
inx
|
||||
cpx #BankPatchNum
|
||||
bcc :dobank
|
||||
|
||||
ldx #0
|
||||
:dopage ldy PagePatches,x ; patch the page addresses by adding the page offset to each
|
||||
lda [:target],y
|
||||
clc
|
||||
adc :target+1
|
||||
sta [:target],y
|
||||
inx
|
||||
inx
|
||||
cpx #PagePatchNum
|
||||
bcc :dopage
|
||||
|
||||
:out
|
||||
rep #$20
|
||||
rts
|
||||
Loading…
Reference in New Issue
Block a user