mirror of
https://github.com/RetroPortingToolKit/psxrecomp
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Matthew Stanley
7ae052534a
Port the reusable Gaussian interpolation slice from PR #16 while keeping its reverb engine on a separate branch. Co-authored-by: Martin Penkava <mpenkava1337@gmail.com> Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
105 lines
6.0 KiB
C
105 lines
6.0 KiB
C
/* spu_gauss.h - PS1 SPU hardware Gaussian interpolation table (512 entries).
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* Values from No$PSX docs / DuckStation core/spu.cpp (SPU::Voice::Interpolate).
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* Usage, with i = (phase >> 4) & 0xFF and s[0]=current, s[-1..-3]=history:
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* out = (g[0x0FF-i]*s[-3] + g[0x1FF-i]*s[-2] + g[0x100+i]*s[-1] + g[i]*s[0]) >> 15
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*/
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#ifndef PSX_SPU_GAUSS_H
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#define PSX_SPU_GAUSS_H
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#include <stdint.h>
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static const int16_t spu_gauss_table[512] = {
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-1, -1, -1, -1, -1, -1, -1, -1,
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-1, -1, -1, -1, -1, -1, -1, -1,
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0, 0, 0, 0, 0, 0, 0, 1,
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1, 1, 1, 2, 2, 2, 3, 3,
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3, 4, 4, 5, 5, 6, 7, 7,
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8, 9, 9, 10, 11, 12, 13, 14,
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15, 16, 17, 18, 19, 21, 22, 24,
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25, 27, 28, 30, 32, 33, 35, 37,
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39, 41, 44, 46, 48, 51, 53, 56,
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58, 61, 64, 67, 70, 73, 77, 80,
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84, 87, 91, 95, 99, 103, 107, 111,
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116, 120, 125, 130, 135, 140, 145, 150,
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156, 161, 167, 173, 179, 186, 192, 199,
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205, 212, 219, 227, 234, 242, 250, 257,
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266, 274, 283, 291, 300, 309, 319, 328,
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338, 348, 358, 369, 379, 390, 401, 412,
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424, 436, 448, 460, 473, 485, 498, 512,
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525, 539, 553, 567, 582, 597, 612, 627,
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643, 659, 675, 692, 708, 726, 743, 761,
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779, 797, 816, 835, 854, 874, 894, 914,
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935, 956, 977, 999, 1020, 1043, 1066, 1089,
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1112, 1136, 1160, 1184, 1209, 1234, 1260, 1286,
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1312, 1339, 1366, 1394, 1422, 1450, 1479, 1508,
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1537, 1567, 1598, 1628, 1660, 1691, 1723, 1756,
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1789, 1822, 1856, 1890, 1924, 1959, 1995, 2031,
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2067, 2104, 2141, 2179, 2217, 2256, 2295, 2334,
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2374, 2415, 2456, 2497, 2539, 2582, 2624, 2668,
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2712, 2756, 2801, 2846, 2892, 2938, 2985, 3032,
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3079, 3128, 3176, 3225, 3275, 3325, 3376, 3427,
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3479, 3531, 3584, 3637, 3691, 3745, 3799, 3855,
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3910, 3967, 4023, 4081, 4138, 4197, 4255, 4315,
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4374, 4435, 4495, 4557, 4619, 4681, 4744, 4807,
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4871, 4935, 5000, 5065, 5131, 5197, 5264, 5332,
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5399, 5468, 5536, 5606, 5676, 5746, 5817, 5888,
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5959, 6032, 6104, 6177, 6251, 6325, 6400, 6475,
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6550, 6626, 6702, 6779, 6856, 6934, 7012, 7091,
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7170, 7249, 7329, 7409, 7490, 7571, 7653, 7735,
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7817, 7900, 7983, 8066, 8150, 8234, 8319, 8404,
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8489, 8575, 8661, 8748, 8834, 8922, 9009, 9097,
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9185, 9273, 9362, 9451, 9541, 9630, 9720, 9811,
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9901, 9992, 10083, 10174, 10266, 10358, 10450, 10542,
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10635, 10727, 10820, 10913, 11007, 11100, 11194, 11288,
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11382, 11476, 11571, 11665, 11760, 11855, 11950, 12045,
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12140, 12236, 12331, 12427, 12522, 12618, 12714, 12809,
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12905, 13001, 13097, 13193, 13289, 13385, 13481, 13577,
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13673, 13769, 13865, 13961, 14056, 14152, 14248, 14343,
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14439, 14534, 14630, 14725, 14820, 14915, 15010, 15104,
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15199, 15293, 15387, 15481, 15575, 15669, 15762, 15855,
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15948, 16041, 16133, 16226, 16317, 16409, 16500, 16592,
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16682, 16773, 16863, 16953, 17042, 17131, 17220, 17308,
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17396, 17484, 17571, 17658, 17744, 17830, 17916, 18001,
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18086, 18170, 18254, 18337, 18420, 18502, 18584, 18665,
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18746, 18826, 18905, 18985, 19063, 19141, 19219, 19295,
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19372, 19447, 19522, 19597, 19671, 19744, 19816, 19888,
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19959, 20030, 20100, 20169, 20238, 20306, 20373, 20439,
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20505, 20570, 20634, 20698, 20760, 20822, 20884, 20944,
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21004, 21063, 21121, 21178, 21235, 21290, 21345, 21399,
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21452, 21505, 21556, 21607, 21657, 21706, 21754, 21801,
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21848, 21893, 21938, 21982, 22025, 22066, 22107, 22148,
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22187, 22225, 22262, 22299, 22334, 22369, 22402, 22435,
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22467, 22498, 22527, 22556, 22584, 22611, 22637, 22662,
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22686, 22709, 22731, 22752, 22772, 22791, 22809, 22826,
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22842, 22857, 22872, 22885, 22897, 22908, 22918, 22927,
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22935, 22942, 22948, 22953, 22957, 22960, 22962, 22963,
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};
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/* Interpolate the current decoded sample using the SPU's four-tap Gaussian
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* filter. previous[] is the final three samples from the preceding ADPCM
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* block, oldest first; sample_index must address samples[]. */
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static inline int16_t spu_gaussian_interpolate(const int16_t previous[3],
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const int16_t samples[28],
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int sample_index,
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uint32_t phase)
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{
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const int gaussian_index = (int)((phase >> 4) & 0xFFu);
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static const int tap_offset[4] = { 3, 2, 1, 0 };
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int32_t accumulator = 0;
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for (int tap = 0; tap < 4; ++tap) {
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const int offset = sample_index - tap_offset[tap];
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const int16_t sample = offset >= 0 ? samples[offset]
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: previous[3 + offset];
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int coefficient_index;
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switch (tap) {
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case 0: coefficient_index = 0x0FF - gaussian_index; break;
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case 1: coefficient_index = 0x1FF - gaussian_index; break;
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case 2: coefficient_index = 0x100 + gaussian_index; break;
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default: coefficient_index = gaussian_index; break;
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}
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accumulator += (int32_t)spu_gauss_table[coefficient_index] * sample;
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}
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return (int16_t)(accumulator >> 15);
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}
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#endif /* PSX_SPU_GAUSS_H */
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