1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/tools/mktables.c	Fri Mar 13 00:39:12 2009 -0700
     1.3 @@ -0,0 +1,88 @@
     1.4 +#include <stdlib.h>
     1.5 +#include <stdio.h>
     1.6 +#include <math.h>
     1.7 +
     1.8 +/*
     1.9 +Pin Eight standard tuning defines middle C as 2093/8 Hz.
    1.10 +It uses equal temperament: a semitone difference between two pitches
    1.11 +is a factor of 2^(1/12) between their frequencies.
    1.12 +Thus, MIDI 0 = 60, or 2093/256.
    1.13 +*/
    1.14 +#define C_IN_OCTAVE(octave) \
    1.15 +  ((double)((long int)2093 << octave) / 256.0)
    1.16 +#define TWELFTH_ROOT_OF_TWO 1.0594630943592952645618252949463
    1.17 +
    1.18 +/*
    1.19 +DS note frequencies for the tone generator at 8 samples per period
    1.20 +are ((-0x1000000 / (n * 8)))
    1.21 +*/
    1.22 +#define FREQ_TO_PSG_PERIOD(freq) \
    1.23 +  ((unsigned short)(-0x1000000 / (freq * 8)))
    1.24 +
    1.25 +  
    1.26 +int writePSG(FILE *fp) {
    1.27 +
    1.28 +  // write header  
    1.29 +  fputs(".section .rodata\n"
    1.30 +        ".balign 4\n"
    1.31 +        ".global midi2psgFreq\n"
    1.32 +        "midi2psgFreq:", fp);
    1.33 +  
    1.34 +  int octave = 0;
    1.35 +  
    1.36 +  for (; octave < 2; ++octave) {
    1.37 +    fprintf(fp, "\n@ unsupported octave %d\n.byte ", octave);
    1.38 +    for (int semitone = 0; semitone < 12; ++semitone) {
    1.39 +      if (semitone) {
    1.40 +        fputs(", ", fp);
    1.41 +      }
    1.42 +      fputs("  0,  0", fp);
    1.43 +    }
    1.44 +  }
    1.45 +  for (; octave < 10; ++octave) {
    1.46 +    double freq = C_IN_OCTAVE(octave);
    1.47 +    fprintf(fp, "\n@ octave %d\n.byte ", octave);
    1.48 +    for (int semitone = 0; semitone < 12; ++semitone) {
    1.49 +      if (semitone) {
    1.50 +        fputs(", ", fp);
    1.51 +        freq *= TWELFTH_ROOT_OF_TWO;
    1.52 +      }
    1.53 +      unsigned int psgFreq = FREQ_TO_PSG_PERIOD(freq);
    1.54 +      printf("midi %2d = %.2f = psg %5d\n",
    1.55 +             octave * 12 + semitone,
    1.56 +             freq,
    1.57 +             psgFreq);
    1.58 +      fprintf(fp, "%3u,%3u",
    1.59 +              psgFreq & 0xFF,
    1.60 +              (psgFreq >> 8) & 0xFF);
    1.61 +    }    
    1.62 +  }
    1.63 +  
    1.64 +  fputs("\n", fp);
    1.65 +  return 0;
    1.66 +}
    1.67 +
    1.68 +/**
    1.69 + * Writes lookup tables used by the ARM7 code.
    1.70 + * Currently, these include the PSG pitch values.
    1.71 + */
    1.72 +int writeARM7(const char *filename) {
    1.73 +  FILE *fp = fopen(filename, "wt");
    1.74 +  if (!fp) {
    1.75 +    return -1;
    1.76 +  }
    1.77 +  if (writePSG(fp) < 0) {
    1.78 +    fclose(fp);
    1.79 +    return -1;
    1.80 +  }
    1.81 +  fclose(fp);
    1.82 +  return 0;
    1.83 +}
    1.84 +
    1.85 +
    1.86 +int main(void) {
    1.87 +  if (writeARM7("obj/ds/lookup_tables7.s") < 0) {
    1.88 +    return EXIT_FAILURE;
    1.89 +  }
    1.90 +  return EXIT_SUCCESS;
    1.91 +}