166 lines
9.8 KiB
C++
166 lines
9.8 KiB
C++
// Altirra - Atari 800/800XL/5200 emulator
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// Copyright (C) 2008-2011 Avery Lee
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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#include "at/ataudio/pokeytables.h"
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ATPokeyTables::ATPokeyTables() {
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// The 4-bit and 5-bit polynomial counters are of the XNOR variety, which means
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// that the all-1s case causes a lockup. The INIT mode shifts zeroes into the
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// register.
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uint32 poly4 = 0;
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for(int i=0; i<131071; ++i) {
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poly4 = (poly4+poly4) + (~((poly4 >> 2) ^ (poly4 >> 3)) & 1);
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mPolyBuffer[i] = (poly4 & 1) << 3;
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}
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uint32 poly5 = 0;
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for(int i=0; i<131071; ++i) {
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poly5 = (poly5+poly5) + (~((poly5 >> 2) ^ (poly5 >> 4)) & 1);
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mPolyBuffer[i] |= (poly5 & 1) << 2;
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}
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// The 17-bit polynomial counter is also of the XNOR variety, but one big
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// difference is that you're allowed to read out 8 bits of it. The RANDOM
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// register actually reports the INVERTED state of these bits (the Q' output
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// of the flip flops is connected to the data bus). This means that even
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// though we clear the register to 0, it reads as FF.
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//
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// From the perspective of the CPU through RANDOM, the LFSR shifts to the
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// right, and new bits appear on the left. The equivalent operation for the
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// 9-bit LFSR would be to set carry equal to (D0 ^ D5) and then execute
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// a ROR.
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uint32 poly9 = 0;
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for(int i=0; i<131071; ++i) {
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// Note: This one is actually verified against a real Atari.
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// At WSYNC time, the pattern goes: 00 DF EE 16 B9....
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poly9 = (poly9 >> 1) + (~((poly9 << 8) ^ (poly9 << 3)) & 0x100);
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mPolyBuffer[i] |= (poly9 & 1) << 1;
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}
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// The 17-bit mode inserts an additional 8 register bits immediately after
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// the XNOR. The generator polynomial is unchanged.
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uint32 poly17 = 0;
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for(int i=0; i<131071; ++i) {
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poly17 = (poly17 >> 1) + (~((poly17 << 16) ^ (poly17 << 11)) & 0x10000);
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mPolyBuffer[i] |= (poly17 >> 8) & 1;
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}
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memcpy(mPolyBuffer + 131071, mPolyBuffer, 131071);
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memset(mInitModeBuffer, 0xFF, sizeof mInitModeBuffer);
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}
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constexpr ATPokeyHiFilterTable ATMakePokeyHiFilterTable() {
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constexpr double kRawFilter[][8] = {
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// Coefficients for a windowed-sinc LPF at 24KHz cutoff with Kaiser window. Scilab derivation:
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//
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// pi=atan(1)*4; fc = 24000/(7159090/2); M=sinc(2*pi*fc*[-223:1:223]).*(2*fc).*window('kr',447,8.6); plot(M); M2=matrix(cat(2,[0],M),[56 8]);
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// mprintf("{ %10.7ff, %10.7ff, %10.7ff, %10.7ff, %10.7ff, %10.7ff, %10.7ff, %10.7ff, },\n", M2)
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// [hm, fr] = frmag(M, 1024); plot(fr, hm)
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{ 0.0000000f, 0.0000885f, -0.0009574f, 0.0030938f, 0.0134095f, 0.0030938f, -0.0009574f, 0.0000885f, },
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{ 0.0000001f, 0.0000887f, -0.0009856f, 0.0033114f, 0.0134045f, 0.0028807f, -0.0009282f, 0.0000879f, },
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{ 0.0000002f, 0.0000886f, -0.0010127f, 0.0035331f, 0.0133893f, 0.0026721f, -0.0008981f, 0.0000870f, },
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{ 0.0000003f, 0.0000880f, -0.0010385f, 0.0037588f, 0.0133641f, 0.0024683f, -0.0008673f, 0.0000858f, },
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{ 0.0000005f, 0.0000870f, -0.0010629f, 0.0039882f, 0.0133288f, 0.0022694f, -0.0008359f, 0.0000844f, },
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{ 0.0000007f, 0.0000856f, -0.0010857f, 0.0042211f, 0.0132836f, 0.0020756f, -0.0008041f, 0.0000827f, },
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{ 0.0000009f, 0.0000836f, -0.0011068f, 0.0044572f, 0.0132284f, 0.0018870f, -0.0007718f, 0.0000808f, },
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{ 0.0000012f, 0.0000811f, -0.0011260f, 0.0046964f, 0.0131635f, 0.0017037f, -0.0007393f, 0.0000787f, },
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{ 0.0000016f, 0.0000780f, -0.0011431f, 0.0049382f, 0.0130888f, 0.0015259f, -0.0007067f, 0.0000764f, },
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{ 0.0000020f, 0.0000743f, -0.0011581f, 0.0051825f, 0.0130046f, 0.0013537f, -0.0006740f, 0.0000740f, },
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{ 0.0000024f, 0.0000700f, -0.0011707f, 0.0054289f, 0.0129110f, 0.0011872f, -0.0006414f, 0.0000715f, },
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{ 0.0000030f, 0.0000651f, -0.0011808f, 0.0056771f, 0.0128081f, 0.0010264f, -0.0006090f, 0.0000689f, },
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{ 0.0000036f, 0.0000594f, -0.0011882f, 0.0059269f, 0.0126961f, 0.0008714f, -0.0005767f, 0.0000662f, },
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{ 0.0000042f, 0.0000531f, -0.0011927f, 0.0061779f, 0.0125751f, 0.0007223f, -0.0005448f, 0.0000635f, },
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{ 0.0000049f, 0.0000460f, -0.0011942f, 0.0064298f, 0.0124455f, 0.0005791f, -0.0005133f, 0.0000607f, },
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{ 0.0000058f, 0.0000381f, -0.0011926f, 0.0066822f, 0.0123074f, 0.0004419f, -0.0004823f, 0.0000579f, },
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{ 0.0000066f, 0.0000294f, -0.0011876f, 0.0069349f, 0.0121610f, 0.0003106f, -0.0004518f, 0.0000551f, },
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{ 0.0000076f, 0.0000199f, -0.0011791f, 0.0071875f, 0.0120066f, 0.0001852f, -0.0004218f, 0.0000523f, },
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{ 0.0000087f, 0.0000095f, -0.0011669f, 0.0074396f, 0.0118444f, 0.0000658f, -0.0003926f, 0.0000495f, },
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{ 0.0000098f, -0.0000017f, -0.0011508f, 0.0076910f, 0.0116746f, -0.0000476f, -0.0003640f, 0.0000467f, },
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{ 0.0000111f, -0.0000138f, -0.0011308f, 0.0079411f, 0.0114977f, -0.0001552f, -0.0003362f, 0.0000440f, },
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{ 0.0000124f, -0.0000269f, -0.0011067f, 0.0081898f, 0.0113138f, -0.0002568f, -0.0003092f, 0.0000413f, },
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{ 0.0000139f, -0.0000408f, -0.0010782f, 0.0084366f, 0.0111233f, -0.0003527f, -0.0002830f, 0.0000387f, },
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{ 0.0000154f, -0.0000558f, -0.0010453f, 0.0086812f, 0.0109264f, -0.0004427f, -0.0002577f, 0.0000361f, },
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{ 0.0000170f, -0.0000716f, -0.0010078f, 0.0089232f, 0.0107235f, -0.0005271f, -0.0002332f, 0.0000336f, },
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{ 0.0000188f, -0.0000884f, -0.0009656f, 0.0091622f, 0.0105149f, -0.0006058f, -0.0002097f, 0.0000312f, },
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{ 0.0000206f, -0.0001062f, -0.0009185f, 0.0093980f, 0.0103009f, -0.0006791f, -0.0001871f, 0.0000289f, },
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{ 0.0000225f, -0.0001250f, -0.0008664f, 0.0096301f, 0.0100819f, -0.0007468f, -0.0001654f, 0.0000267f, },
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{ 0.0000246f, -0.0001447f, -0.0008092f, 0.0098581f, 0.0098581f, -0.0008092f, -0.0001447f, 0.0000246f, },
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{ 0.0000267f, -0.0001654f, -0.0007468f, 0.0100819f, 0.0096301f, -0.0008664f, -0.0001250f, 0.0000225f, },
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{ 0.0000289f, -0.0001871f, -0.0006791f, 0.0103009f, 0.0093980f, -0.0009185f, -0.0001062f, 0.0000206f, },
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{ 0.0000312f, -0.0002097f, -0.0006058f, 0.0105149f, 0.0091622f, -0.0009656f, -0.0000884f, 0.0000188f, },
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{ 0.0000336f, -0.0002332f, -0.0005271f, 0.0107235f, 0.0089232f, -0.0010078f, -0.0000716f, 0.0000170f, },
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{ 0.0000361f, -0.0002577f, -0.0004427f, 0.0109264f, 0.0086812f, -0.0010453f, -0.0000558f, 0.0000154f, },
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{ 0.0000387f, -0.0002830f, -0.0003527f, 0.0111233f, 0.0084366f, -0.0010782f, -0.0000408f, 0.0000139f, },
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{ 0.0000413f, -0.0003092f, -0.0002568f, 0.0113138f, 0.0081898f, -0.0011067f, -0.0000269f, 0.0000124f, },
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{ 0.0000440f, -0.0003362f, -0.0001552f, 0.0114977f, 0.0079411f, -0.0011308f, -0.0000138f, 0.0000111f, },
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{ 0.0000467f, -0.0003640f, -0.0000476f, 0.0116746f, 0.0076910f, -0.0011508f, -0.0000017f, 0.0000098f, },
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{ 0.0000495f, -0.0003926f, 0.0000658f, 0.0118444f, 0.0074396f, -0.0011669f, 0.0000095f, 0.0000087f, },
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{ 0.0000523f, -0.0004218f, 0.0001852f, 0.0120066f, 0.0071875f, -0.0011791f, 0.0000199f, 0.0000076f, },
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{ 0.0000551f, -0.0004518f, 0.0003106f, 0.0121610f, 0.0069349f, -0.0011876f, 0.0000294f, 0.0000066f, },
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{ 0.0000579f, -0.0004823f, 0.0004419f, 0.0123074f, 0.0066822f, -0.0011926f, 0.0000381f, 0.0000058f, },
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{ 0.0000607f, -0.0005133f, 0.0005791f, 0.0124455f, 0.0064298f, -0.0011942f, 0.0000460f, 0.0000049f, },
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{ 0.0000635f, -0.0005448f, 0.0007223f, 0.0125751f, 0.0061779f, -0.0011927f, 0.0000531f, 0.0000042f, },
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{ 0.0000662f, -0.0005767f, 0.0008714f, 0.0126961f, 0.0059269f, -0.0011882f, 0.0000594f, 0.0000036f, },
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{ 0.0000689f, -0.0006090f, 0.0010264f, 0.0128081f, 0.0056771f, -0.0011808f, 0.0000651f, 0.0000030f, },
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{ 0.0000715f, -0.0006414f, 0.0011872f, 0.0129110f, 0.0054289f, -0.0011707f, 0.0000700f, 0.0000024f, },
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{ 0.0000740f, -0.0006740f, 0.0013537f, 0.0130046f, 0.0051825f, -0.0011581f, 0.0000743f, 0.0000020f, },
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{ 0.0000764f, -0.0007067f, 0.0015259f, 0.0130888f, 0.0049382f, -0.0011431f, 0.0000780f, 0.0000016f, },
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{ 0.0000787f, -0.0007393f, 0.0017037f, 0.0131635f, 0.0046964f, -0.0011260f, 0.0000811f, 0.0000012f, },
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{ 0.0000808f, -0.0007718f, 0.0018870f, 0.0132284f, 0.0044572f, -0.0011068f, 0.0000836f, 0.0000009f, },
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{ 0.0000827f, -0.0008041f, 0.0020756f, 0.0132836f, 0.0042211f, -0.0010857f, 0.0000856f, 0.0000007f, },
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{ 0.0000844f, -0.0008359f, 0.0022694f, 0.0133288f, 0.0039882f, -0.0010629f, 0.0000870f, 0.0000005f, },
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{ 0.0000858f, -0.0008673f, 0.0024683f, 0.0133641f, 0.0037588f, -0.0010385f, 0.0000880f, 0.0000003f, },
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{ 0.0000870f, -0.0008981f, 0.0026721f, 0.0133893f, 0.0035331f, -0.0010127f, 0.0000886f, 0.0000002f, },
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{ 0.0000879f, -0.0009282f, 0.0028807f, 0.0134045f, 0.0033114f, -0.0009856f, 0.0000887f, 0.0000001f, },
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};
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static_assert(vdcountof(kRawFilter) == 56);
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ATPokeyHiFilterTable table {};
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for(int i=0; i<=28; ++i) {
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float sum = 0;
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for(int j=0; j<8; ++j) {
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table.mFilter[i][j] = (float)kRawFilter[i][7-j];
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sum += table.mFilter[i][j];
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}
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float scale = 1.0f / sum;
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for(float& v : table.mFilter[i])
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v *= scale;
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}
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return table;
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}
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constexpr ATPokeyHiFilterTable ATMakePokeyHiFilterTable2() {
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constexpr ATPokeyHiFilterTable table = ATMakePokeyHiFilterTable();
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return table;
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}
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extern const ATPokeyHiFilterTable g_ATPokeyHiFilterTable = ATMakePokeyHiFilterTable2();
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