Index: apps/plugins/pitch_detector.c
===================================================================
--- apps/plugins/pitch_detector.c	(Revision 22700)
+++ apps/plugins/pitch_detector.c	(Arbeitskopie)
@@ -177,6 +177,43 @@
     float2fixed(0.45),
     float2fixed(0.50),
 };
+
+/* Index of the entry for 440 Hz in the tables (default frequency for A) */
+#define DEFAULT_REFERENCE 5 /* 440 */
+
+/* Frequency of A normalised to 440Hz, i.e. xxx/440 */
+const fixed freq_A [] =
+{
+    float2fixed(0.988636364), /* 435 Hz */
+    float2fixed(0.990909091),
+    float2fixed(0.993181818),
+    float2fixed(0.995454545),
+    float2fixed(0.997727273),
+    float2fixed(1),           /* 440 Hz */
+    float2fixed(1.002272727),
+    float2fixed(1.004545455),
+    float2fixed(1.006818182),
+    float2fixed(1.009090909),
+    float2fixed(1.011363636), /* 445 Hz */
+};
+
+/* Log (to base 2) of Frequency of A normalised to 440Hz,
+ * i.e. log2(xxx/440)
+ */
+const fixed lfreq_A [] =
+{
+    float2fixed(-0.016488123), /* 435 Hz */
+    float2fixed(-0.013175389),
+    float2fixed(-0.009870244),
+    float2fixed(-0.006572654),
+    float2fixed(-0.003282584),
+    float2fixed( 0),           /* 440 Hz reference standard A */
+    float2fixed( 0.003275132),
+    float2fixed( 0.006542846),
+    float2fixed( 0.009803175),
+    float2fixed( 0.013056153),
+    float2fixed( 0.016301812), /* 445 Hz */
+};
 
 /* How loud the audio has to be to start displaying pitch  */
 /* Must be between 0 and 100                               */
@@ -279,6 +316,7 @@
     unsigned sample_size;
     unsigned lowest_freq;
     unsigned yin_threshold;
+    unsigned freq_A; /* Index of the frequency of A */
     bool use_sharps;
     bool display_hz;
 } tuner_settings;
@@ -325,6 +363,7 @@
     settings->sample_size = BUFFER_SIZE;
     settings->lowest_freq = period2freq(BUFFER_SIZE / 4);
     settings->yin_threshold = DEFAULT_YIN_THRESHOLD;
+    settings->freq_A = DEFAULT_REFERENCE;
     settings->use_sharps = true;
     settings->display_hz = false;
 }
@@ -426,6 +465,23 @@
     { "0.50", -1 },
 };
 
+/* These are the display frequency options for note A */
+
+static const struct opt_items freq_A_text[] =
+{
+    { "435", -1 },
+    { "436", -1 },
+    { "437", -1 },
+    { "438", -1 },
+    { "439", -1 },
+    { "440", -1 },
+    { "441", -1 },
+    { "442", -1 },
+    { "443", -1 },
+    { "444", -1 },
+    { "445", -1 },
+};
+
 static const struct opt_items accidental_text[] = 
 {
     { "Flat", -1 },
@@ -469,6 +525,7 @@
                         "Accidentals",
                         "Display Frequency (Hz)",
                         "Reset Settings",
+                        "Frequency of A (Hz)",
                         "Quit");
 
     while(!done)
@@ -519,13 +576,20 @@
                                BOOL, noyes_text, 2, tuner_settings_reset_query);
                 break;
             case 8:
+                rb->set_option(
+                    "Frequency of A (Hz)",
+                    &tuner_settings.freq_A,
+                    INT, freq_A_text,
+                    sizeof(freq_A_text) / sizeof(freq_A_text[0]),
+                    NULL);
+                break;
+            case 9:
                 exit_tuner = true;
             case 0: 
             default:
                 /* Return to the tuner */
                 done = true;
                 break;
-
         }
     }
     return(exit_tuner);
@@ -650,11 +714,11 @@
     int x;
 
 #ifdef HAVE_LCD_COLOR
-    rb->lcd_set_foreground(LCD_RGBPACK(255,255,255));	/* Color screens */
+    rb->lcd_set_foreground(LCD_RGBPACK(255,255,255)); /* Color screens */
 #elif LCD_DEPTH > 1
     rb->lcd_set_foreground(LCD_BLACK);      /* Greyscale screens */
 #else
-    rb->lcd_set_foreground(LCD_BLACK);		/* Black and white screens */
+    rb->lcd_set_foreground(LCD_BLACK);      /* Black and white screens */
 #endif
 
     rb->lcd_hline(0,LCD_WIDTH-1, BAR_HLINE_Y);
@@ -708,25 +772,29 @@
     if (fp_lt(freq, FP_LOW))
         freq = FP_LOW;
     lfreq = log(freq);
-
-    /* Get the frequency to within the range of our reference table */
-    while (fp_lt(lfreq, fp_sub(lfreqs[0], fp_shr(LOG_D_NOTE, 1))))
+    fixed lfreq_A_offset;
+    /* This calculates a log freq offset for note A */
+    lfreq_A_offset = lfreq_A[tuner_settings.freq_A];
+    /* Get the frequency to within the range of our freq_A table */
+    while (fp_lt(lfreq, fp_sub(fp_add(lfreqs[0],lfreq_A_offset), fp_shr(LOG_D_NOTE, 1))))
         lfreq = fp_add(lfreq, LOG_2);
-    while (fp_gte(lfreq, fp_sub(fp_add(lfreqs[0], LOG_2), 
+    while (fp_gte(lfreq, fp_sub(fp_add(fp_add(lfreqs[0],lfreq_A_offset), LOG_2),
            fp_shr(LOG_D_NOTE, 1))))
         lfreq = fp_sub(lfreq, LOG_2);
     mldf = LOG_D_NOTE;
-    for (i=0; i<12; i++) 
+    for (i=0; i<12; i++)
     {
-        ldf = fp_gt(fp_sub(lfreq,lfreqs[i]), FP_ZERO) ? 
-                 fp_sub(lfreq,lfreqs[i]) : fp_neg(fp_sub(lfreq,lfreqs[i]));
-        if (fp_lt(ldf, mldf)) 
+        ldf = fp_gt(fp_sub(lfreq,fp_add(lfreqs[i],lfreq_A_offset)), FP_ZERO) ? 
+                 fp_sub(lfreq,fp_add(lfreqs[i],lfreq_A_offset)) :
+                 fp_neg(fp_sub(lfreq,fp_add(lfreqs[i],lfreq_A_offset)));
+        if (fp_lt(ldf, mldf))
         {
-              mldf = ldf;
-              note = i;
+            mldf = ldf;
+            note = i;
         }
     }
-    nfreq = freqs[note];
+    /* this scales the calulated note by the freq offset for note A */
+    nfreq = (fp_mul(freqs[note],freq_A[tuner_settings.freq_A]));
     while (fp_gt(fp_div(nfreq, freq), D_NOTE_SQRT)) 
         nfreq = fp_shr(nfreq, 1);
     while (fp_gt(fp_div(freq, nfreq), D_NOTE_SQRT))
@@ -734,7 +802,7 @@
         nfreq = fp_shl(nfreq, 1);
     }
     
-    ldf=fp_mul(int2fixed(1200), log(fp_div(freq,nfreq)));
+    ldf = fp_mul(int2fixed(1200), log(fp_div(freq,nfreq)));
 
     rb->lcd_clear_display();
     draw_bar(ldf);                /* The red bar */