review fixes: refactoring and readme update

README.md

@@ -111,6 +111,7 @@ openFPGALoader -- a program to flash cyclone10 LP FPGA
   -b, --board=BOARD          board name, may be used instead of cable
   -c, --cable=CABLE          jtag interface
   -d, --device=DEVICE        device to use (/dev/ttyUSBx)
+      --ftdi-channel=CHANNEL FTDI chip channel number (channels 0-3 map to A-D)
       --detect               detect FPGA
       --freq=FREQ            jtag frequency (Hz)
   -f, --write-flash          write bitstream in flash (default: false, only for

src/cable.hpp

@@ -22,20 +22,6 @@ typedef struct {
 	FTDIpp_MPSSE::mpsse_bit_config config;
 } cable_t;
 
-inline int ftdi_update_channel(cable_t &cable, unsigned int channel_num)
-{
-	int mapping[] = {INTERFACE_A,INTERFACE_B, INTERFACE_C, INTERFACE_D};
-	
-	if (cable.type != MODE_FTDI_SERIAL && cable.type != MODE_FTDI_BITBANG)
-		return -1;
-
-	if (channel_num > 3)
-		return -2;
-
-	cable.config.interface = mapping[channel_num];
-	return 0;
-}
-
 static std::map <std::string, cable_t> cable_list = {
 	// last 4 bytes are ADBUS7-0 value, ADBUS7-0 direction, ACBUS7-0 value, ACBUS7-0 direction
 	// some cables requires explicit values on some of the I/Os

src/main.cpp

@@ -116,15 +116,13 @@ int main(int argc, char **argv)
 	cable = select_cable->second;
 
 	if (args.ftdi_channel != -1) {
-		if (args.ftdi_channel < 0 or args.ftdi_channel > 3) {
+		if (cable.type != MODE_FTDI_SERIAL && cable.type != MODE_FTDI_BITBANG){
-			printError("Error: valid FTDI channels are 0-3.");
+			printError("Error: FTDI channel param is for FTDI cables.");
 			return EXIT_FAILURE;
 		}
 
-		if (ftdi_update_channel(cable, args.ftdi_channel)) {
+		int mapping[] = {INTERFACE_A, INTERFACE_B, INTERFACE_C, INTERFACE_D};
-			printError("Error: FTDI channel param is invalid. Is it a FTDI cable?");
+		cable.config.interface = mapping[args.ftdi_channel];
-			return EXIT_FAILURE;
-		}
 	}
 
 	/* jtag base */
@@ -262,7 +260,7 @@ int parse_opt(int argc, char **argv, struct arguments *args, jtag_pins_conf_t *p
 			("b,board",     "board name, may be used instead of cable",
 				cxxopts::value<string>(args->board))
 			("c,cable", "jtag interface", cxxopts::value<string>(args->cable))
-			("ftdi_channel", "FTDI chip channel number (channels 0-3 map to A-D)", cxxopts::value<int>(args->ftdi_channel))
+			("ftdi-channel", "FTDI chip channel number (channels 0-3 map to A-D)", cxxopts::value<int>(args->ftdi_channel))
 #ifdef USE_UDEV
 			("d,device",  "device to use (/dev/ttyUSBx)",
 				cxxopts::value<string>(args->device))
@@ -331,6 +329,13 @@ int parse_opt(int argc, char **argv, struct arguments *args, jtag_pins_conf_t *p
 			args->freq = static_cast<uint32_t>(freq);
 		}
 
+		if (result.count("ftdi-channel")) {
+			if (args->ftdi_channel < 0 || args->ftdi_channel > 3) {
+				printError("Error: valid FTDI channels are 0-3.");
+				throw std::exception();
+			}
+		}
+
 		if (result.count("pins")) {
 			if (pins.size() != 4) {
 				printError("Error: pin_config need 4 pins");