211 lines
3.2 KiB
ArmAsm
211 lines
3.2 KiB
ArmAsm
; FP registers in zero page
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FR0 = $d4
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FRE = $da
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FR1 = $e0
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FR2 = $e6
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FRX = $ec
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EEXP = $ed
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NSIGN = $ee
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ESIGN = $ef
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FLPTR = $fc
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FPTR2 = $fe
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; FP routines
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AFP = $D800
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FASC = $D8E6
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IFP = $D9AA
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FIP = $D9D2
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ZFR0 = $DA44
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ZFI = $DA46
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FSUB = $DA60
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FADD = $DA66
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FMUL = $DADB
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FDIV = $DB28
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PLYVEL = $DD40
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FLD0R = $DD49 ; from pointer in X/Y
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FLD0P = $DD89 ; from pointer in FLPTR
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FLD1R = $DD89
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FLD1P = $DD9c
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FST0R = $DDA7
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FST0P = $DDAB
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FMOVE = $DDB6 ; FR0 -> FR1
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EXP = $DDC0
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EXP10 = $DDCC
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LOG = $decd
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LOG10 = $ded1
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.code
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.export start
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.proc start
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loop:
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jmp loop
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.endproc
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.proc mandelfloat
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.endproc
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.macro sext16to32 arg
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.local plus
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.local minus
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lda arg+1
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bpl plus
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lda #$ff
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jmp minus
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plus:
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lda #$00
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minus:
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sta arg+2
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sta arg+3
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.endmacro
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.macro copy bytes, arg1, arg2
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.repeat 2, byte
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lda arg1+byte
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sta arg2+byte
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.endrepeat
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.endmacro
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.macro copy16 arg1, arg2
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copy 2, arg1, arg2
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.endmacro
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.macro copy32 arg1, arg2
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copy 4, arg1, arg2
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.endmacro
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.macro add bytes, arg1, arg2
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clc
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.repeat bytes, byte
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lda arg1+byte
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adc arg2+byte
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sta arg1+byte
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.endrepeat
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.endmacro
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.macro add16 arg1, arg2
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add 2, arg1, arg2
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.endmacro
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.macro add32 arg1, arg2
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add 4, arg1, arg2
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.endmacro
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.macro shl bytes, arg
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asl arg
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.repeat bytes-1, byte
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rol arg+byte+1
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.endrepeat
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.endmacro
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.macro shl16 arg
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shl 2, arg
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.endmacro
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.macro shl24 arg
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shl 3, arg
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.endmacro
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.macro shl32 arg
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shl 4, arg
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.endmacro
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.macro shr bytes, arg
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lsr arg
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.repeat bytes-1, byte
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ror arg+byte+1
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.endrepeat
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.endmacro
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.macro shr16 arg
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shr 2, arg
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.endmacro
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.macro shr24 arg
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shr 3, arg
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.endmacro
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.macro shr32 arg
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shr 4, arg
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.endmacro
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.macro bitmul16 arg1, arg2, result, bitnum
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.local next
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clc
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; check if arg1 has 0 or 1 bit in this place
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.if bitnum < 8
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lda arg1
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and #(1 << bitnum)
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.else
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lda arg1 + 1
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and #(1 << (bitnum - 8))
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.endif
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beq next
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; 16-bit add on the top bits
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lda result + 2
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adc arg2
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sta result + 2
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lda result + 3
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adc arg2 + 1
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sta result + 3
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next:
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; Shift the 32-bit result down by one bit,
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; saving the previous carry.
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ror result + 3
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ror result + 2
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ror result + 1
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.if bitnum >= 8
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; we can save 5 cycles * 8 bits = 40 cycles total by skipping this byte
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; when it's all uninitialized data
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ror result
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.endif
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.endmacro
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.proc imul16
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; 16-bit arg in FR0
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; 16-bit arg in FR1
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; 32-bit result in FR2
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; zero out the 32-bit temp's top 16 bits
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lda #0
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sta FR2 + 2
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sta FR2 + 3
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; the bottom two bytes will get cleared by the shifts
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.repeat 16, bitnum
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bitmul16 FR0, FR1, FR2, bitnum
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.endrepeat
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rts
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.endproc
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.proc iter
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; (cx and cy should be pre-scaled to 6.26 fixed point)
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; zx = 0
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; zx_2 = 0
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; zy = 0
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; zx_2 = 0
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loop:
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; iters++
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; zx_next = zx_2 + zy_2 + cx
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; zy_next = 2 * zx * zy + cy
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; (detect overflows to -4 or +4 and break if necessary)
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; (re-downshift into zx and zy as 3.13 fixed point; round.)
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; zx_2 = zx * zx
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; zy_2 = zy * zy
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; dist = zx_2 + zy_2
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; if dist >= 4 break, else continue iterating
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.endproc
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