-/* Convert linear signal-to-noise ratio into dB */
-static u8 ratio2dB[100] = {
-/* 0 1 2 3 4 5 6 7 8 9 */
- 0, 0, 6, 10, 12, 14, 16, 17, 18, 19, /* 00 - 09 */
- 20, 21, 22, 22, 23, 23, 24, 25, 26, 26, /* 10 - 19 */
- 26, 26, 26, 27, 27, 28, 28, 28, 29, 29, /* 20 - 29 */
- 29, 30, 30, 30, 31, 31, 31, 31, 32, 32, /* 30 - 39 */
- 32, 32, 32, 33, 33, 33, 33, 33, 34, 34, /* 40 - 49 */
- 34, 34, 34, 34, 35, 35, 35, 35, 35, 35, /* 50 - 59 */
- 36, 36, 36, 36, 36, 36, 36, 37, 37, 37, /* 60 - 69 */
- 37, 37, 37, 37, 37, 38, 38, 38, 38, 38, /* 70 - 79 */
- 38, 38, 38, 38, 38, 39, 39, 39, 39, 39, /* 80 - 89 */
- 39, 39, 39, 39, 39, 40, 40, 40, 40, 40 /* 90 - 99 */
-};
-
-/* Calculates a relative dB value from a ratio of linear
- * (i.e. not dB) signal levels.
- * Conversion assumes that levels are voltages (20*log), not powers (10*log). */
-int iwl4965_calc_db_from_ratio(int sig_ratio)
-{
- /* 1000:1 or higher just report as 60 dB */
- if (sig_ratio >= 1000)
- return 60;
-
- /* 100:1 or higher, divide by 10 and use table,
- * add 20 dB to make up for divide by 10 */
- if (sig_ratio >= 100)
- return (20 + (int)ratio2dB[sig_ratio/10]);
-
- /* We shouldn't see this */
- if (sig_ratio < 1)
- return 0;
-
- /* Use table for ratios 1:1 - 99:1 */
- return (int)ratio2dB[sig_ratio];
-}
-
-#define PERFECT_RSSI (-20) /* dBm */
-#define WORST_RSSI (-95) /* dBm */
-#define RSSI_RANGE (PERFECT_RSSI - WORST_RSSI)
-
-/* Calculate an indication of rx signal quality (a percentage, not dBm!).
- * See http://www.ces.clemson.edu/linux/signal_quality.shtml for info
- * about formulas used below. */
-int iwl4965_calc_sig_qual(int rssi_dbm, int noise_dbm)
-{
- int sig_qual;
- int degradation = PERFECT_RSSI - rssi_dbm;
-
- /* If we get a noise measurement, use signal-to-noise ratio (SNR)
- * as indicator; formula is (signal dbm - noise dbm).
- * SNR at or above 40 is a great signal (100%).
- * Below that, scale to fit SNR of 0 - 40 dB within 0 - 100% indicator.
- * Weakest usable signal is usually 10 - 15 dB SNR. */
- if (noise_dbm) {
- if (rssi_dbm - noise_dbm >= 40)
- return 100;
- else if (rssi_dbm < noise_dbm)
- return 0;
- sig_qual = ((rssi_dbm - noise_dbm) * 5) / 2;
-
- /* Else use just the signal level.
- * This formula is a least squares fit of data points collected and
- * compared with a reference system that had a percentage (%) display
- * for signal quality. */
- } else
- sig_qual = (100 * (RSSI_RANGE * RSSI_RANGE) - degradation *
- (15 * RSSI_RANGE + 62 * degradation)) /
- (RSSI_RANGE * RSSI_RANGE);
-
- if (sig_qual > 100)
- sig_qual = 100;
- else if (sig_qual < 1)
- sig_qual = 0;
-
- return sig_qual;
-}