Curve.cpp

/* 
 * File:   Curve.cpp
 * Author: cameron
 * 
 * Created on October 22, 2013, 1:07 AM
 */

#include "Curve.h"

// If this wasn't in program memory, we'd run out of SRAM way to fast.
const uint8_t Curve::etable[256] PROGMEM = {
   0,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
   1,  1,  1,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,
   2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  3,  3,  3,  3,  3,
   3,  3,  3,  3,  3,  3,  3,  3,  3,  3,  4,  4,  4,  4,  4,  4,
   4,  4,  4,  4,  4,  4,  5,  5,  5,  5,  5,  5,  5,  5,  5,  6,
   6,  6,  6,  6,  6,  6,  6,  7,  7,  7,  7,  7,  7,  8,  8,  8,
   8,  8,  8,  9,  9,  9,  9,  9, 10, 10, 10, 10, 10, 11, 11, 11,
  11, 12, 12, 12, 12, 13, 13, 13, 14, 14, 14, 14, 15, 15, 15, 16,
  16, 16, 17, 17, 18, 18, 18, 19, 19, 20, 20, 21, 21, 21, 22, 22,
  23, 23, 24, 24, 25, 25, 26, 27, 27, 28, 28, 29, 30, 30, 31, 32,
  32, 33, 34, 35, 35, 36, 37, 38, 39, 39, 40, 41, 42, 43, 44, 45,
  46, 47, 48, 49, 50, 51, 52, 53, 55, 56, 57, 58, 59, 61, 62, 63,
  65, 66, 68, 69, 71, 72, 74, 76, 77, 79, 81, 82, 84, 86, 88, 90,
  92, 94, 96, 98,100,102,105,107,109,112,114,117,119,122,124,127,
 130,133,136,139,142,145,148,151,155,158,162,165,169,172,176,180,
 184,188,192,196,201,205,210,214,219,224,229,234,239,244,250,255,
};


uint8_t Curve::exponential(uint8_t i) {
 // If the compiler could build the above table for us, we could have "simply":
 //return !i ? 0 : round(exp(log(MAXOUTPUT) * i / MAXINPUT));
 
 // Need to read the table in a special way!
 return pgm_read_byte(&etable[i]);
}

uint8_t Curve::linear(uint8_t i) {
 return i;
}

uint8_t Curve::reverse(uint8_t i) {
 return 255-i;
}