diff --git a/bitmul.s b/bitmul.s new file mode 100644 index 0000000..df84704 --- /dev/null +++ b/bitmul.s @@ -0,0 +1,124 @@ +; the old 16-bit bit-and-shift multiplier +; copied from old code, won't compile as-is + +; inner loop for imul16 +; bitnum < 8: 25 or 41 cycles +; bitnum >= 8: 30 or 46 cycles +.macro bitmul16 arg1, arg2, result, bitnum + .local zero + .local one + .local next + + ; does 16-bit adds + ; arg1 and arg2 are treated as unsigned + ; negative signed inputs must be flipped first + + ; 7 cycles up to the branch + + ; check if arg1 has 0 or 1 bit in this place + ; 5 cycles either way + .if bitnum < 8 + lda arg1 ; 3 cyc + and #(1 << (bitnum)) ; 2 cyc + .else + lda arg1 + 1 ; 3 cyc + and #(1 << ((bitnum) - 8)) ; 2 cyc + .endif + bne one ; 2 cyc + +zero: ; 18 cyc, 23 cyc + lsr result + 3 ; 5 cyc + jmp next ; 3 cyc + +one: ; 32 cyc, 37 cyc + ; 16-bit add on the top bits + clc ; 2 cyc + lda result + 2 ; 3 cyc + adc arg2 ; 3 cyc + sta result + 2 ; 3 cyc + lda result + 3 ; 3 cyc + adc arg2 + 1 ; 3 cyc + ror a ; 2 cyc - get a jump on the shift + sta result + 3 ; 3 cyc +next: + ror result + 2 ; 5 cyc + ror result + 1 ; 5 cyc + .if bitnum >= 8 + ; we can save 5 cycles * 8 bits = 40 cycles total by skipping this byte + ; when it's all uninitialized data + ror result ; 5 cyc + .endif + +.endmacro + +; 5 to 25 cycles +.macro check_sign arg + ; Check sign bit and flip argument to postive, + ; keeping a count of sign bits in the X register. + .local positive + lda arg + 1 ; 3 cyc + bpl positive ; 2 cyc + neg16 arg ; 18 cyc + inx ; 2 cyc +positive: +.endmacro + +; 518 - 828 cyc +.macro imul16 dest, arg1, arg2 + copy16 FR0, arg1 ; 12 cyc + copy16 FR1, arg2 ; 12 cyc + jsr imul16_func ; 470-780 cyc + copy32 dest, FR2 ; 24 cyc +.endmacro + + +.macro shift_round_16 arg, shift + .repeat shift + shl32 arg + .endrepeat + round16 arg +.endmacro + +.macro imul16_round dest, arg1, arg2, shift + copy16 FR0, arg1 ; 12 cyc + copy16 FR1, arg2 ; 12 cyc + jsr imul16_func ; 470-780 cyc + shift_round_16 FR2, shift + copy16 dest, FR2 + 2 ; 12 cyc +.endmacro + +; min 470 cycles +; max 780 cycles +.proc imul16_func + arg1 = FR0 ; 16-bit arg (clobbered) + arg2 = FR1 ; 16-bit arg (clobbered) + result = FR2 ; 32-bit result + + ldx #0 ; 2 cyc + ; counts the number of sign bits in X + check_sign arg1 ; 5 to 25 cyc + check_sign arg2 ; 5 to 25 cyc + + ; zero out the 32-bit temp's top 16 bits + lda #0 ; 2 cyc + sta result + 2 ; 3 cyc + sta result + 3 ; 3 cyc + ; the bottom two bytes will get cleared by the shifts + + ; unrolled loop for maximum speed, at the cost + ; of a larger routine + ; 440 to 696 cycles + .repeat 16, bitnum + ; bitnum < 8: 25 or 41 cycles + ; bitnum >= 8: 30 or 46 cycles + bitmul16 arg1, arg2, result, bitnum + .endrepeat + + ; In case of mixed input signs, return a negative result. + cpx #1 ; 2 cyc + bne positive_result ; 2 cyc + neg32 result ; 34 cyc +positive_result: + + rts ; 6 cyc +.endproc diff --git a/mandel-core.s b/mandel-core.s index 34dff8b..5080d7e 100644 --- a/mandel-core.s +++ b/mandel-core.s @@ -563,12 +563,13 @@ sqr16_patch_offset = 8 ; input: arg as u8 ; output: dest as u16 ; clobbers a, x +; 19 cyc .macro sqr8 dest, arg - ldx arg - lda sqr_lobyte,x - sta dest - lda sqr_hibyte,x - sta dest + 1 + ldx arg ; 3 cyc + lda sqr_lobyte,x ; 5 cyc + sta dest ; 3 cyc + lda sqr_hibyte,x ; 5 cyc + sta dest + 1 ; 3 cyc .endmacro .segment "TABLES" @@ -770,6 +771,10 @@ inner_loop: .endproc +; min low-mem: 81 * 4 + 28 * 2 + 10 + 6 = 396 cyc +; max low-mem: 92 * 4 + 28 * 2 + 50 + 6 = 480 cyc +; min ext-mem: 51 * 4 + 28 * 2 + 10 + 6 = 276 cyc +; max low-mem: 70 * 4 + 28 * 2 + 50 + 6 = 392 cyc .macro imul16_impl xe .local arg1 .local arg2 @@ -787,32 +792,37 @@ inner_loop: ; h1*256*(h2*256 + l2) + l1*(h2*256 + l2) ; h1*h2*256*256 + h1*l2*256 + h2*l1*256 + l1*l2 - imul8 result, arg1, arg2, xe + imul8 result, arg1, arg2, xe ; 81-92 or 51-70 - imul8 result + 2, arg1 + 1, arg2 + 1, xe + imul8 result + 2, arg1 + 1, arg2 + 1, xe ; 81-92 or 51-70 - imul8 inter, arg1 + 1, arg2, xe - add16 result + 1, result + 1, inter - add_carry result + 3 + imul8 inter, arg1 + 1, arg2, xe ; 81-92 or 51-70 + add16 result + 1, result + 1, inter ; 20 cyc + add_carry result + 3 ; 8 cyc - imul8 inter, arg1, arg2 + 1, xe - add16 result + 1, result + 1, inter - add_carry result + 3 + imul8 inter, arg1, arg2 + 1, xe ; 81-92 or 51-70 + add16 result + 1, result + 1, inter ; 20 cyc + add_carry result + 3 ; 8 cyc ; In case of negative inputs, adjust high word ; https://stackoverflow.com/a/28827013 - lda arg1 + 1 - bpl arg1_pos - sub16 result + 2, result + 2, arg2 + ; 10-50 cycles + lda arg1 + 1 ; 3 cyc + bpl arg1_pos ; 2 cyc + sub16 result + 2, result + 2, arg2 ; 20 cyc arg1_pos: - lda arg2 + 1 - bpl arg2_pos - sub16 result + 2, result + 2, arg1 + lda arg2 + 1 ; 3 cyc + bpl arg2_pos ; 2 cyc + sub16 result + 2, result + 2, arg1 ; 20 cyc arg2_pos: rts ; 6 cyc .endmacro +; min base ram: 19 * 2 + 81 + 28 * 2 + 6 = 181 +; max base ram: 19 * 2 + 92 + 28 * 2 + 6 = 192 +; min ext ram: 19 * 2 + 51 + 28 * 2 + 6 = 151 +; max ext ram: 19 * 2 + 70 + 28 * 2 + 6 = 170 .macro sqr16_impl xe .scope arg = FR0 ; 16-bit arg (clobbered) @@ -820,9 +830,9 @@ arg2_pos: ;inter = temp2 inter = FR1 - lda arg + 1 - bpl arg_pos - neg16 arg + lda arg + 1 ; 3 cyc + bpl arg_pos ; 2 cyc + neg16 arg ; 18 cyc arg_pos: ; hl * hl @@ -830,15 +840,15 @@ arg2_pos: ; h*256*(h*256 + l) + l*(h*256 + l) ; h*h*256*256 + h*l*256 + h*l*256 + l*l - sqr8 result, arg + sqr8 result, arg ; 19 cyc - sqr8 result + 2, arg + 1 + sqr8 result + 2, arg + 1 ; 19 cyc - imul8 inter, arg + 1, arg, xe - add16 result + 1, result + 1, inter - add_carry result + 3 - add16 result + 1, result + 1, inter - add_carry result + 3 + imul8 inter, arg + 1, arg, xe ; 81-92 / 51-70 cyc + add16 result + 1, result + 1, inter ; 20 cyc + add_carry result + 3 ; 8 cyc + add16 result + 1, result + 1, inter ; 20 cyc + add_carry result + 3 ; 8 cyc rts ; 6 cyc .endscope