From 4231c2c83f2b5331e3e38b10a308ee3752315f9c Mon Sep 17 00:00:00 2001 From: Solomon Peachy Date: Sat, 26 Sep 2020 17:19:07 -0400 Subject: codecs: Add support for the 'VTX' ZX Spectrum chiptunes format. This codec requires floating point. Original author: Peter Sovietov Ported to Rockbox: Roman Skylarov Further integration and bugfixes: Solomon Peachy Change-Id: I781ecd3592dfcdbbc694063334350342534f1d6c --- lib/rbcodec/codecs/libayumi/ayumi.c | 361 ++++++++++++++++++++++++++++++++++++ 1 file changed, 361 insertions(+) create mode 100644 lib/rbcodec/codecs/libayumi/ayumi.c (limited to 'lib/rbcodec/codecs/libayumi/ayumi.c') diff --git a/lib/rbcodec/codecs/libayumi/ayumi.c b/lib/rbcodec/codecs/libayumi/ayumi.c new file mode 100644 index 0000000000..2e0419f6cb --- /dev/null +++ b/lib/rbcodec/codecs/libayumi/ayumi.c @@ -0,0 +1,361 @@ +/* Author: Peter Sovietov */ + +#include +#include +#include "ayumi.h" + +static const double AY_dac_table[] = { + 0.0, 0.0, + 0.00999465934234, 0.00999465934234, + 0.0144502937362, 0.0144502937362, + 0.0210574502174, 0.0210574502174, + 0.0307011520562, 0.0307011520562, + 0.0455481803616, 0.0455481803616, + 0.0644998855573, 0.0644998855573, + 0.107362478065, 0.107362478065, + 0.126588845655, 0.126588845655, + 0.20498970016, 0.20498970016, + 0.292210269322, 0.292210269322, + 0.372838941024, 0.372838941024, + 0.492530708782, 0.492530708782, + 0.635324635691, 0.635324635691, + 0.805584802014, 0.805584802014, + 1.0, 1.0 +}; + +static const double YM_dac_table[] = { + 0.0, 0.0, + 0.00465400167849, 0.00772106507973, + 0.0109559777218, 0.0139620050355, + 0.0169985503929, 0.0200198367285, + 0.024368657969, 0.029694056611, + 0.0350652323186, 0.0403906309606, + 0.0485389486534, 0.0583352407111, + 0.0680552376593, 0.0777752346075, + 0.0925154497597, 0.111085679408, + 0.129747463188, 0.148485542077, + 0.17666895552, 0.211551079576, + 0.246387426566, 0.281101701381, + 0.333730067903, 0.400427252613, + 0.467383840696, 0.53443198291, + 0.635172045472, 0.75800717174, + 0.879926756695, 1.0 +}; + +static void reset_segment(struct ayumi* ay); + +double sqrt(double n) +{ + double x0 = n; + double x1; + for (;;) { + x1 = x0 - (x0 * x0 - n) / (2 * x0); + double delta = (x1 - x0) / x0; + if (delta < .000001 && delta > -.000001) + return x1; + x0 = x1; + } +} + +static int update_tone(struct ayumi* ay, int index) { + struct tone_channel* ch = &ay->channels[index]; + ch->tone_counter += 1; + if (ch->tone_counter >= ch->tone_period) { + ch->tone_counter = 0; + ch->tone ^= 1; + } + return ch->tone; +} + +static int update_noise(struct ayumi* ay) { + int bit0x3; + ay->noise_counter += 1; + if (ay->noise_counter >= (ay->noise_period << 1)) { + ay->noise_counter = 0; + bit0x3 = ((ay->noise ^ (ay->noise >> 3)) & 1); + ay->noise = (ay->noise >> 1) | (bit0x3 << 16); + } + return ay->noise & 1; +} + +static void slide_up(struct ayumi* ay) { + ay->envelope += 1; + if (ay->envelope > 31) { + ay->envelope_segment ^= 1; + reset_segment(ay); + } +} + +static void slide_down(struct ayumi* ay) { + ay->envelope -= 1; + if (ay->envelope < 0) { + ay->envelope_segment ^= 1; + reset_segment(ay); + } +} + +static void hold_top(struct ayumi* ay) { + (void) ay; +} + +static void hold_bottom(struct ayumi* ay) { + (void) ay; +} + +static void (* const Envelopes[][2])(struct ayumi*) = { + {slide_down, hold_bottom}, + {slide_down, hold_bottom}, + {slide_down, hold_bottom}, + {slide_down, hold_bottom}, + {slide_up, hold_bottom}, + {slide_up, hold_bottom}, + {slide_up, hold_bottom}, + {slide_up, hold_bottom}, + {slide_down, slide_down}, + {slide_down, hold_bottom}, + {slide_down, slide_up}, + {slide_down, hold_top}, + {slide_up, slide_up}, + {slide_up, hold_top}, + {slide_up, slide_down}, + {slide_up, hold_bottom} +}; + +static void reset_segment(struct ayumi* ay) { + if (Envelopes[ay->envelope_shape][ay->envelope_segment] == slide_down + || Envelopes[ay->envelope_shape][ay->envelope_segment] == hold_top) { + ay->envelope = 31; + return; + } + ay->envelope = 0; +} + +int update_envelope(struct ayumi* ay) { + ay->envelope_counter += 1; + if (ay->envelope_counter >= ay->envelope_period) { + ay->envelope_counter = 0; + Envelopes[ay->envelope_shape][ay->envelope_segment](ay); + } + return ay->envelope; +} + +static void update_mixer(struct ayumi* ay) { + int i; + int out; + int noise = update_noise(ay); + int envelope = update_envelope(ay); + ay->left = 0; + ay->right = 0; + for (i = 0; i < TONE_CHANNELS; i += 1) { + out = (update_tone(ay, i) | ay->channels[i].t_off) & (noise | ay->channels[i].n_off); + out *= ay->channels[i].e_on ? envelope : ay->channels[i].volume * 2 + 1; + ay->left += ay->dac_table[out] * ay->channels[i].pan_left; + ay->right += ay->dac_table[out] * ay->channels[i].pan_right; + } +} + +int ayumi_configure(struct ayumi* ay, int is_ym, double clock_rate, int sr) { + int i; + memset(ay, 0, sizeof(struct ayumi)); + ay->step = clock_rate / (sr * 8 * DECIMATE_FACTOR); + ay->dac_table = is_ym ? YM_dac_table : AY_dac_table; + ay->noise = 1; + ayumi_set_envelope(ay, 1); + for (i = 0; i < TONE_CHANNELS; i += 1) { + ayumi_set_tone(ay, i, 1); + } + return ay->step < 1; +} + +void ayumi_set_pan(struct ayumi* ay, int index, double pan, int is_eqp) { + if (is_eqp) { + ay->channels[index].pan_left = sqrt(1 - pan); + ay->channels[index].pan_right = sqrt(pan); + } else { + ay->channels[index].pan_left = 1 - pan; + ay->channels[index].pan_right = pan; + } +} + +void ayumi_set_tone(struct ayumi* ay, int index, int period) { + period &= 0xfff; + ay->channels[index].tone_period = (period == 0) | period; +} + +void ayumi_set_noise(struct ayumi* ay, int period) { + ay->noise_period = period & 0x1f; +} + +void ayumi_set_mixer(struct ayumi* ay, int index, int t_off, int n_off, int e_on) { + ay->channels[index].t_off = t_off & 1; + ay->channels[index].n_off = n_off & 1; + ay->channels[index].e_on = e_on; +} + +void ayumi_set_volume(struct ayumi* ay, int index, int volume) { + ay->channels[index].volume = volume & 0xf; +} + +void ayumi_set_envelope(struct ayumi* ay, int period) { + period &= 0xffff; + ay->envelope_period = (period == 0) | period; +} + +void ayumi_set_envelope_shape(struct ayumi* ay, int shape) { + ay->envelope_shape = shape & 0xf; + ay->envelope_counter = 0; + ay->envelope_segment = 0; + reset_segment(ay); +} + +static double decimate(double* x) { + double y = -0.0000046183113992051936 * (x[1] + x[191]) + + -0.00001117761640887225 * (x[2] + x[190]) + + -0.000018610264502005432 * (x[3] + x[189]) + + -0.000025134586135631012 * (x[4] + x[188]) + + -0.000028494281690666197 * (x[5] + x[187]) + + -0.000026396828793275159 * (x[6] + x[186]) + + -0.000017094212558802156 * (x[7] + x[185]) + + 0.000023798193576966866 * (x[9] + x[183]) + + 0.000051281160242202183 * (x[10] + x[182]) + + 0.00007762197826243427 * (x[11] + x[181]) + + 0.000096759426664120416 * (x[12] + x[180]) + + 0.00010240229300393402 * (x[13] + x[179]) + + 0.000089344614218077106 * (x[14] + x[178]) + + 0.000054875700118949183 * (x[15] + x[177]) + + -0.000069839082210680165 * (x[17] + x[175]) + + -0.0001447966132360757 * (x[18] + x[174]) + + -0.00021158452917708308 * (x[19] + x[173]) + + -0.00025535069106550544 * (x[20] + x[172]) + + -0.00026228714374322104 * (x[21] + x[171]) + + -0.00022258805927027799 * (x[22] + x[170]) + + -0.00013323230495695704 * (x[23] + x[169]) + + 0.00016182578767055206 * (x[25] + x[167]) + + 0.00032846175385096581 * (x[26] + x[166]) + + 0.00047045611576184863 * (x[27] + x[165]) + + 0.00055713851457530944 * (x[28] + x[164]) + + 0.00056212565121518726 * (x[29] + x[163]) + + 0.00046901918553962478 * (x[30] + x[162]) + + 0.00027624866838952986 * (x[31] + x[161]) + + -0.00032564179486838622 * (x[33] + x[159]) + + -0.00065182310286710388 * (x[34] + x[158]) + + -0.00092127787309319298 * (x[35] + x[157]) + + -0.0010772534348943575 * (x[36] + x[156]) + + -0.0010737727700273478 * (x[37] + x[155]) + + -0.00088556645390392634 * (x[38] + x[154]) + + -0.00051581896090765534 * (x[39] + x[153]) + + 0.00059548767193795277 * (x[41] + x[151]) + + 0.0011803558710661009 * (x[42] + x[150]) + + 0.0016527320270369871 * (x[43] + x[149]) + + 0.0019152679330965555 * (x[44] + x[148]) + + 0.0018927324805381538 * (x[45] + x[147]) + + 0.0015481870327877937 * (x[46] + x[146]) + + 0.00089470695834941306 * (x[47] + x[145]) + + -0.0010178225878206125 * (x[49] + x[143]) + + -0.0020037400552054292 * (x[50] + x[142]) + + -0.0027874356824117317 * (x[51] + x[141]) + + -0.003210329988021943 * (x[52] + x[140]) + + -0.0031540624117984395 * (x[53] + x[139]) + + -0.0025657163651900345 * (x[54] + x[138]) + + -0.0014750752642111449 * (x[55] + x[137]) + + 0.0016624165446378462 * (x[57] + x[135]) + + 0.0032591192839069179 * (x[58] + x[134]) + + 0.0045165685815867747 * (x[59] + x[133]) + + 0.0051838984346123896 * (x[60] + x[132]) + + 0.0050774264697459933 * (x[61] + x[131]) + + 0.0041192521414141585 * (x[62] + x[130]) + + 0.0023628575417966491 * (x[63] + x[129]) + + -0.0026543507866759182 * (x[65] + x[127]) + + -0.0051990251084333425 * (x[66] + x[126]) + + -0.0072020238234656924 * (x[67] + x[125]) + + -0.0082672928192007358 * (x[68] + x[124]) + + -0.0081033739572956287 * (x[69] + x[123]) + + -0.006583111539570221 * (x[70] + x[122]) + + -0.0037839040415292386 * (x[71] + x[121]) + + 0.0042781252851152507 * (x[73] + x[119]) + + 0.0084176358598320178 * (x[74] + x[118]) + + 0.01172566057463055 * (x[75] + x[117]) + + 0.013550476647788672 * (x[76] + x[116]) + + 0.013388189369997496 * (x[77] + x[115]) + + 0.010979501242341259 * (x[78] + x[114]) + + 0.006381274941685413 * (x[79] + x[113]) + + -0.007421229604153888 * (x[81] + x[111]) + + -0.01486456304340213 * (x[82] + x[110]) + + -0.021143584622178104 * (x[83] + x[109]) + + -0.02504275058758609 * (x[84] + x[108]) + + -0.025473530942547201 * (x[85] + x[107]) + + -0.021627310017882196 * (x[86] + x[106]) + + -0.013104323383225543 * (x[87] + x[105]) + + 0.017065133989980476 * (x[89] + x[103]) + + 0.036978919264451952 * (x[90] + x[102]) + + 0.05823318062093958 * (x[91] + x[101]) + + 0.079072012081405949 * (x[92] + x[100]) + + 0.097675998716952317 * (x[93] + x[99]) + + 0.11236045936950932 * (x[94] + x[98]) + + 0.12176343577287731 * (x[95] + x[97]) + + 0.125 * x[96]; + memcpy(&x[FIR_SIZE - DECIMATE_FACTOR], x, DECIMATE_FACTOR * sizeof(double)); + return y; +} + +void ayumi_process(struct ayumi* ay) { + int i; + double y1; + double* c_left = ay->interpolator_left.c; + double* y_left = ay->interpolator_left.y; + double* c_right = ay->interpolator_right.c; + double* y_right = ay->interpolator_right.y; + double* fir_left = &ay->fir_left[FIR_SIZE - ay->fir_index * DECIMATE_FACTOR]; + double* fir_right = &ay->fir_right[FIR_SIZE - ay->fir_index * DECIMATE_FACTOR]; + ay->fir_index = (ay->fir_index + 1) % (FIR_SIZE / DECIMATE_FACTOR - 1); + for (i = DECIMATE_FACTOR - 1; i >= 0; i -= 1) { + ay->x += ay->step; + if (ay->x >= 1) { + ay->x -= 1; + y_left[0] = y_left[1]; + y_left[1] = y_left[2]; + y_left[2] = y_left[3]; + y_right[0] = y_right[1]; + y_right[1] = y_right[2]; + y_right[2] = y_right[3]; + update_mixer(ay); + y_left[3] = ay->left; + y_right[3] = ay->right; + y1 = y_left[2] - y_left[0]; + c_left[0] = 0.5 * y_left[1] + 0.25 * (y_left[0] + y_left[2]); + c_left[1] = 0.5 * y1; + c_left[2] = 0.25 * (y_left[3] - y_left[1] - y1); + y1 = y_right[2] - y_right[0]; + c_right[0] = 0.5 * y_right[1] + 0.25 * (y_right[0] + y_right[2]); + c_right[1] = 0.5 * y1; + c_right[2] = 0.25 * (y_right[3] - y_right[1] - y1); + } + fir_left[i] = (c_left[2] * ay->x + c_left[1]) * ay->x + c_left[0]; + fir_right[i] = (c_right[2] * ay->x + c_right[1]) * ay->x + c_right[0]; + } + ay->left = decimate(fir_left); + ay->right = decimate(fir_right); +} + +void ayumi_seek(struct ayumi* ay) { + int i; + for (i = DECIMATE_FACTOR - 1; i >= 0; i -= 1) { + ay->x += ay->step; + if (ay->x >= 1) { + ay->x -= 1; + update_mixer(ay); + } + } +} + +static double dc_filter(struct dc_filter* dc, int index, double x) { + dc->sum += -dc->delay[index] + x; + dc->delay[index] = x; + return x - dc->sum / DC_FILTER_SIZE; +} + +void ayumi_remove_dc(struct ayumi* ay) { + ay->left = dc_filter(&ay->dc_left, ay->dc_index, ay->left); + ay->right = dc_filter(&ay->dc_right, ay->dc_index, ay->right); + ay->dc_index = (ay->dc_index + 1) & (DC_FILTER_SIZE - 1); +} -- cgit v1.2.3