fixing iso14443b (issue #103):

- fix: IQ demodulator (FPGA)
- fix: approximately align reader signal delay to tag response delay (FPGA)
- fix: remove deprecated RSSI calculation to improve decoder speed (iso14443b.c)
- fix: better approximation of signal amplitude to avoid false carrier detection (iso14443b.c)
- fix: remove initial power off in iso14443b raw command (iso14443b.c)
- add: enable tracing for iso14443b raw command (iso14443b.c)
- fix: client crashed when checking CRC for incomplete responses (iso14433b.c)
- speeding up snoop to avoid circular buffer overflow
- added some comments for better documentation
- rename functions (iso14443 -> iso14443b)
- remove unused code in hi_read_rx_xcorr.v

fpga/fpga_hf.v

@@ -67,15 +67,10 @@ assign major_mode = conf_word[7:5];
 // some fraction of the buffers)
 wire hi_read_tx_shallow_modulation = conf_word[0];
 
-// For the high-frequency receive correlator: frequency against which to
-// correlate.
-wire hi_read_rx_xcorr_848 = conf_word[0];
-// and whether to drive the coil (reader) or just short it (snooper)
+// For the high-frequency receive correlator:
+// whether to drive the coil (reader) or just short it (snooper)
 wire hi_read_rx_xcorr_snoop = conf_word[1];
 
-// Divide the expected subcarrier frequency for hi_read_rx_xcorr by 4
-wire hi_read_rx_xcorr_quarter = conf_word[2];
-
 // For the high-frequency simulated tag: what kind of modulation to use.
 wire [2:0] hi_simulate_mod_type = conf_word[2:0];
 
@@ -102,7 +97,7 @@ hi_read_rx_xcorr hrxc(
 	hrxc_ssp_frame, hrxc_ssp_din, ssp_dout, hrxc_ssp_clk,
 	cross_hi, cross_lo,
 	hrxc_dbg,
-	hi_read_rx_xcorr_848, hi_read_rx_xcorr_snoop, hi_read_rx_xcorr_quarter
+	hi_read_rx_xcorr_snoop
 );
 
 hi_simulate hs(