chore: delta symbol

nanovna.h

@@ -144,6 +144,7 @@ extern int area_height;
 extern const uint8_t x5x7_bits [];
 extern const uint8_t numfont20x22[][22 * 3];
 
+#define S_DELTA "\004"
 #define S_PI    "\034"
 #define S_MICRO "\035"
 #define S_OHM   "\036"

plot.c

@@ -756,34 +756,34 @@ trace_get_value_string_delta(int t, char *buf, int len, float array[101][2], int
   case TRC_LOGMAG:
     v = logmag(coeff) - logmag(coeff_ref);
     if (v == -INFINITY)
-      chsnprintf(buf, len, "\004-INF dB");
+      chsnprintf(buf, len, S_DELTA "-INF dB");
     else
-      chsnprintf(buf, len, "\004%.2fdB", v);
+      chsnprintf(buf, len, S_DELTA "%.2fdB", v);
     break;
   case TRC_PHASE:
     v = phase(coeff) - phase(coeff_ref);
-    chsnprintf(buf, len, "\004%.2f" S_DEGREE, v);
+    chsnprintf(buf, len, S_DELTA "%.2f" S_DEGREE, v);
     break;
   case TRC_DELAY:
     v = groupdelay_from_array(index, array) - groupdelay_from_array(index_ref, array);
     string_value_with_prefix(buf, len, v, 's');
     break;
   case TRC_LINEAR:
     v = linear(coeff) - linear(coeff_ref);
-    chsnprintf(buf, len, "\004%.2f", v);
+    chsnprintf(buf, len, S_DELTA "%.2f", v);
     break;
   case TRC_SWR:
     v = swr(coeff) - swr(coeff_ref);
-    chsnprintf(buf, len, "\004%.2f", v);
+    chsnprintf(buf, len, S_DELTA "%.2f", v);
     break;
   case TRC_SMITH:
     format_smith_value(buf, len, coeff, frequencies[index]);
     break;
   case TRC_REAL:
-    chsnprintf(buf, len, "\004%.2f", coeff[0] - coeff_ref[0]);
+    chsnprintf(buf, len, S_DELTA "%.2f", coeff[0] - coeff_ref[0]);
     break;
   case TRC_IMAG:
-    chsnprintf(buf, len, "\004%.2fj", coeff[1] - coeff_ref[1]);
+    chsnprintf(buf, len, S_DELTA "%.2fj", coeff[1] - coeff_ref[1]);
     break;
   case TRC_R:
     gamma2resistance(buf, len, coeff);
@@ -1594,7 +1594,7 @@ cell_draw_marker_info(int m, int n, int w, int h)
       int32_t freq = frequencies[markers[mk].index];
       if (uistat.marker_delta && mk != active_marker) {
         freq -= frequencies[markers[active_marker].index];
-        frequency_string_short(buf, sizeof buf, freq, '\004');
+        frequency_string_short(buf, sizeof buf, freq, S_DELTA[0]);
       } else {
         frequency_string_short(buf, sizeof buf, freq, 0);
       }
@@ -1615,7 +1615,8 @@ cell_draw_marker_info(int m, int n, int w, int h)
       int ypos = 1 + (j/2)*7;
       xpos -= m * CELLWIDTH -CELLOFFSETX;
       ypos -= n * CELLHEIGHT;
-      chsnprintf(buf, sizeof buf, "\004%d:", previous_marker+1);
+      strcpy(buf, S_DELTA "1:");
+      buf[1] += previous_marker;
       cell_drawstring_5x7(w, h, buf, xpos, ypos, 0xffff);
       xpos += 19;
       if ((domain_mode & DOMAIN_MODE) == DOMAIN_FREQ) {
@@ -1655,7 +1656,8 @@ cell_draw_marker_info(int m, int n, int w, int h)
     int ypos = 1 + (j/2)*7;
     xpos -= m * CELLWIDTH -CELLOFFSETX;
     ypos -= n * CELLHEIGHT;
-    chsnprintf(buf, sizeof buf, "%d:", active_marker + 1);
+    strcpy(buf, "1:");
+    buf[0] += active_marker;
     xpos += 5;
     cell_drawstring_invert_5x7(w, h, buf, xpos, ypos, 0xffff, uistat.lever_mode == LM_MARKER);
     xpos += 14;