First inroads to turbo8
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cnlohr
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8e628ab602
commit
b9dc46c701
7 changed files with 384 additions and 6 deletions
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@ -353,6 +353,3 @@ void DoDFTProgressive32( float * outbins, float * frequencies, int bins, const f
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#endif
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264
embeddedcommon/DFT8Turbo.c
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264
embeddedcommon/DFT8Turbo.c
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#include <stdint.h>
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#include <stdlib.h>
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#include "DFT8Turbo.h"
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#include <math.h>
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#include <stdio.h>
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#define MAX_FREQS (24)
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#define OCTAVES (5)
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/*
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* The first thought was using an integration map and only operating when we need to, to pull the data out.
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* Now we're doing the thing below this block comment
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int16_t accumulated_total; //2 bytes
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int16_t last_accumulated_total_at_bin[MAX_FREQS*2]; //24 * 2 * sizeof(int16_t) = 96 bytes.
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uint8_t current_time; //1 byte
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uint8_t placecode[MAX_FREQS];
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*/
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//OK... We don't have enough ram to sum everything... can we do something wacky with multiple ocatives to sum everything better?
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//i.e.
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//
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// 4332322132212210
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//
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// ++++++++++++++++-----------------
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// ++++++++--------
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// ++++----++++----
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// ++--++--++--++--
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// +-+-+-+-+-+-+-+-
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//
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// Don't forget we need to do this for sin and cos.
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// Can we instead of making this plusses, make it a multiplier?
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// How can we handle sin+cos?
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//
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// Is it possible to do this for every frame? I.e. for each of the 24 notes, multiply with their current place in table?
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// That's interesting. It's not like a sin table.
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// There is no "multiply" in the attiny instruction set for attiny85.
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// There is, however for attiny402
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//Question: Can we do five octaves, or does this need to be balanced?
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//Question2: Should we weight higher octaves?
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//ATTiny402: 256x8 RAM, 4096x8 FLASH LPM: 3 cycles + FMUL: 2 cycles << Do stacked sin waves?
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//ATtiny85: 512x8 RAM, 8192x8 FLASH LPM: 3 cycles + NO MULTIPLY << Do square waves?
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/* Approaches:
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on ATtiny402: Stacked sin approach.
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Say 16 MHz, though 12 MHz is interesting...
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16k SPS: 1k cycles per; say 24 bins per; 41 cycles per bin = hard. But is it too hard?
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20 cycles per s/c.
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read place in stacked table (8? bits) 3 cycles
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//Inner loop = 17 cycles.
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read stacked table (8 bits), 3 cycles
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fractional multiply table with current value. 2 cycles
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read current running for note 2 cycles (LDS = 3 cycles)
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subtract a shifted version, to make it into an IIR. (4 cycles)
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add in current values. (2 cycles)
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store data back to ram (2 cycles)
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advance place in stacked table (8?bits) 1 cycle
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store place in stacked table (8? bits) 3 cycles?
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//What if we chunk ADC updates into groups of 4 or 8?
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//This is looking barely possible.
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on attiny85: scheduled adds/subtracts (like a stacked-square-wave-table)
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//XXX TODO!
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*/
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/* Ok... Let's think about the ATTiny402. 256x8 RAM + 4096x8 FLASH.
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* We can create a table which has all octaves overlaid.
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* We would need to keep track of:
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* 12 x 2 x 2 = 48 bytes = Current sin/cos values.
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* 12 x 2 = 24 bytes = Current place in table. = 72 bytes
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* We would need to store:
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* The layered lookup table. If possible, keep @ 256 bytes to simplify math ops.
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* The speed by which each note needs to advance.
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* We would need to:
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* Read current running place. X 8 cycles
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* Use that place to look up into sin table. 3 cycles
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* Read running val 4 cycles best case
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* Multiply out the sin + IIR 5 cycles
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* Store running val 4 cycles best case
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* Cos-advance that place to look up into sin table. 4 cycles
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* Read running val 4 cycles best case
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* Multiply out the sin + IIR 5 cycles
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* Store running val 4 cycles best case.
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* Read how much to advance X by. 4 cycles
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* (Cos^2+Sin^2) 8?
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* Store it. 4 cycles best case.
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* = 48 x 12 = 576 cycles. Assume 10 MHz @ 16k SPS. We're OK (625 samples)
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*/
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// Observation: The two tables are actually mirror images of each other, well diagonally mirrored. That's odd. But, would take CPU to exploit.
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#define SSTABLESIZE 256
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int8_t spikysin_interleved_cos[SSTABLESIZE*2];
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uint16_t advancespeed[MAX_FREQS];
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static int CompTableWithPhase( int nelements, float phase, int scaling )
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{
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int highest = 0;
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int i;
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for( i = 0; i < nelements; i++ )
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{
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float taued = i * 3.141592 * 2.0 / nelements;
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int o;
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float combsin = 0;
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for( o = 0; o < OCTAVES; o++ )
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{
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combsin += sin( taued * (1<<o) + phase);
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}
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combsin /= OCTAVES;
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int csadapt = combsin * scaling; //No value is higher with five octaves. XXX TODO Lookout. If you change # of octaves, need to change this, too.
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if( csadapt > highest ) highest = csadapt;
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if( -csadapt > highest ) highest = -csadapt;
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if( csadapt > 127 ) csadapt = 127;
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if( csadapt < -127 ) csadapt = -127; //tricky: Keep balanced.
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spikysin_interleved_cos[i*2+0] = csadapt;
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float combcos = 0;
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for( o = 0; o < OCTAVES; o++ )
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{
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combcos += cos( taued * (1<<o) + phase );
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}
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combcos /= OCTAVES;
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csadapt = combcos * scaling; //No value is higher with five octaves. XXX TODO Lookout. If you change # of octaves, need to change this, too.
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if( csadapt > highest ) highest = csadapt;
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if( -csadapt > highest ) highest = -csadapt;
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if( csadapt > 127 ) csadapt = 127;
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if( csadapt < -127 ) csadapt = -127; //tricky: Keep balanced.
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spikysin_interleved_cos[i*2+1] = csadapt;
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}
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return highest;
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}
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static int Setup( float * frequencies, int bins )
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{
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int i;
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//Since start position/phase is arbitrary, we should try several to see which gives us the best dynamic range.
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float tryphase = 0;
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float bestphase = 0;
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int highest_val_at_best_phase = 1000000;
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for( tryphase = 0; tryphase < 3.14159; tryphase += 0.001 )
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{
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int highest = CompTableWithPhase( SSTABLESIZE, tryphase, 65536 );
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if( highest < highest_val_at_best_phase )
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{
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highest_val_at_best_phase = highest;
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bestphase = tryphase;
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}
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}
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printf( "Best comp: %f : %d\n", bestphase, highest_val_at_best_phase );
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CompTableWithPhase( SSTABLESIZE, bestphase, (65536*128)/highest_val_at_best_phase );
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// for( i = 0; i < SSTABLESIZE; i++ )
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// {
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// printf( "%d %d\n", spikysin_interleved_cos[i*2+0], spikysin_interleved_cos[i*2+1] );
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// }
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for( i = 0; i < MAX_FREQS; i++ )
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{
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//frequencies[i] = SPS / Freq
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// Need to decide how quickly we sweep through the table.
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advancespeed[i] = 256.0 /* fixed point */ * 256.0 /* size of table */ / frequencies[i];
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//printf( "%f\n", frequencies[i] );
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}
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return 0;
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}
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/*
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uint8_t spikysin_interleved_cos[256*2];
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uint16_t advancespeed[MAX_FREQS];
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*/
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float toutbins[MAX_FREQS];
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struct notedat
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{
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uint16_t time;
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int32_t sinm;
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int32_t cosm;
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};
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static struct notedat nd[MAX_FREQS];
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void Turbo8BitRun( int8_t adcval )
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{
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int i;
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for( i = 0; i < MAX_FREQS; i++ )
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{
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uint16_t ct = nd[i].time;
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int32_t muxres;
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int32_t running;
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int32_t rdesc, rdess;
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int8_t ss = spikysin_interleved_cos[(ct>>8) + 0];
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muxres = ((int16_t)adcval * ss) >> 8;
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running = nd[i].cosm;
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running += muxres;
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rdesc = running >> 8;
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running -= rdesc>>6;
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nd[i].cosm = running;
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int8_t sc = spikysin_interleved_cos[(ct>>8) + 1];
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muxres = ((int16_t)adcval * sc) >> 8;
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running = nd[i].sinm;
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running += muxres;
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rdess = running>>8;
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running -= rdess>>6;
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nd[i].sinm = running;
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nd[i].time = ct + advancespeed[i];
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toutbins[i] = rdess * rdess + rdesc * rdesc;
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//printf( "%d %d = %f %p\n", rdess, rdesc, toutbins[i], &toutbins[i] );
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}
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}
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void DoDFT8BitTurbo( float * outbins, float * frequencies, int bins, const float * databuffer, int place_in_data_buffer, int size_of_data_buffer, float q, float speedup )
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{
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static int is_setup;
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if( !is_setup ) { is_setup = 1; Setup( frequencies, bins ); }
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static int last_place;
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int i;
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for( i = last_place; i != place_in_data_buffer; i = (i+1)%size_of_data_buffer )
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{
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int16_t ifr1 = (int16_t)( ((databuffer[i]) ) * 4095 );
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//ifr1 += 4095;
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Turbo8BitRun( ifr1>>5 );
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}
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for( i = 0; i < bins; i++ )
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{
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outbins[i] = 0;
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}
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for( i = 0; i < MAX_FREQS; i++ )
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{
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int iss = nd[i].sinm;
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int isc = nd[i].cosm;
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int mux = iss * iss + isc * isc;
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if( mux == 0 ) mux = 1;
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outbins[i+MAX_FREQS] = sqrt(mux)/1000.0;
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}
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}
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9
embeddedcommon/DFT8Turbo.h
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9
embeddedcommon/DFT8Turbo.h
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@ -0,0 +1,9 @@
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#ifndef _DFT8TURBO_H
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#define _DFT8TURBO_H
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/* Note: Frequencies must be precompiled. */
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void DoDFT8BitTurbo( float * outbins, float * frequencies, int bins, const float * databuffer, int place_in_data_buffer, int size_of_data_buffer, float q, float speedup );
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#endif
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