feat(miner): scale displayed hashrate units dynamically

utils.c

@@ -15,6 +15,48 @@ static char to_hex_digit(unsigned int v) {
     return (char)('a' + (v - 10U));
 }
 
+static void format_hashrate_core(double rate_hs, char *out, size_t out_len) {
+    static const char *units[] = {"H/s", "kH/s", "MH/s", "GH/s", "TH/s", "PH/s", "EH/s"};
+    size_t unit_idx = 0;
+    const size_t unit_count = sizeof(units) / sizeof(units[0]);
+    double value;
+
+    if (out == NULL || out_len == 0) {
+        return;
+    }
+
+    if (!(rate_hs >= 0.0)) {
+        rate_hs = 0.0;
+    }
+    value = rate_hs;
+
+    while (value >= 999.95 && unit_idx + 1 < unit_count) {
+        value /= 1000.0;
+        unit_idx++;
+    }
+
+    while (value > 0.0 && value < 1.0 && unit_idx > 0) {
+        value *= 1000.0;
+        unit_idx--;
+    }
+
+    if (value >= 100.0) {
+        snprintf(out, out_len, "%.0f %s", value, units[unit_idx]);
+    } else if (value >= 10.0) {
+        snprintf(out, out_len, "%.1f %s", value, units[unit_idx]);
+    } else {
+        snprintf(out, out_len, "%.2f %s", value, units[unit_idx]);
+    }
+}
+
+void format_hashrate_hz(double rate_hz, char *out, size_t out_len) {
+    format_hashrate_core(rate_hz, out, out_len);
+}
+
+void format_hashrate_khs(double rate_khs, char *out, size_t out_len) {
+    format_hashrate_core(rate_khs * 1000.0, out, out_len);
+}
+
 void sb_init(StrBuf *sb) {
     sb->data = NULL;
     sb->len = 0;