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usbscale
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Add argument parsing for selecting scale by index

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master
Eric Jiang 9 months ago
parent 21081b7ee8
commit f8918c7095
1 changed files with 125 additions and 37 deletions
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162
usbscale.c
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@ -10,7 +10,7 @@
//
/*
usbscale
Copyright (C) 2011 Eric Jiang
Copyright (C) 2011--2023 Eric Jiang
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@ -25,12 +25,15 @@ GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <sys/types.h>
#include <stdint.h>
#include <math.h>
#include <argp.h>
#include <errno.h>
#include <math.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
//
// This program uses libusb-1.0 (not the older libusb-0.1) for USB
@ -64,7 +67,7 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
// **find_scale** takes a libusb device list and finds the first USB device
// that matches a device listed in scales.h.
//
static libusb_device* find_scale(libusb_device**);
static libusb_device* find_nth_scale(libusb_device**, int);
//
// **print_scale_data** takes the 6-byte output from the scale and interprets
// it, printing out the result to the screen. It also returns a 1 if the
@ -77,6 +80,10 @@ static int print_scale_data(unsigned char*);
//
uint8_t get_first_endpoint_address(libusb_device* dev);
// **is_scale** checks if the given USB vendor and product IDs are a known scale
// (as defined in scales.h)
bool is_scale(uint16_t idVendor, uint16_t idProduct);
//
// **UNITS** is an array of all the unit abbreviations as set forth by *HID
// Point of Sale Usage Tables*, version 1.02, by the USB Implementers' Forum.
@ -99,19 +106,71 @@ const char* UNITS[13] = {
"lbs" // pound
};
// Setup argument parsing
const char *argp_program_version = "usbscale 0.2";
const char *argp_program_bug_address = "<https://www.github.com/erjiang/usbscale/issues>";
static char doc[] = "Read weight from a USB scale\n"
"The `tare' command will request the scale to reset to zero (not supported by all scales).\n";
static char args_doc[] = "[zero]";
static struct argp_option options[] = {
{ "index", 'i', "INDEX", 0, "Index of scale to read (default: 1)" },
{ 0 }
};
// setup argp to get index
struct arguments {
int index;
bool tare;
};
static error_t parse_opt(int key, char *arg, struct argp_state *state) {
struct arguments *arguments = state->input;
switch (key) {
case 'i':
arguments->index = atoi(arg);
// Make sure index is >0 since the first scale has index 1.
if (arguments->index < 1) {
argp_usage(state);
}
break;
case ARGP_KEY_ARG:
if (strcmp(arg, "zero") == 0) {
arguments->tare = true;
} else {
argp_usage(state);
}
break;
case ARGP_KEY_END:
return 0;
default:
return ARGP_ERR_UNKNOWN;
}
return 0;
}
static struct argp argp = { options, parse_opt, args_doc, doc };
//
// main
// ----
//
int main(int argc, char **argv)
{
// Parse arguments
struct arguments arguments;
// By default, get the first scale's weight
arguments.index = 1;
arguments.tare = false;
argp_parse(&argp, argc, argv, 0, 0, &arguments);
libusb_device **devs;
int r; // holds return codes
ssize_t cnt;
libusb_device* dev;
libusb_device_handle* handle;
int weigh_count = WEIGH_COUNT -1;
int weigh_count = WEIGH_COUNT - 1;
//
// We first try to init libusb.
@ -138,9 +197,12 @@ int main(int argc, char **argv)
// every device against the scales.h list. **find_scale** will return the
// first device that matches, or 0 if none of them matched.
//
dev = find_scale(devs);
dev = find_nth_scale(devs, arguments.index);
if(dev == 0) {
fprintf(stderr, "No USB scale found on this computer.\n");
if (arguments.index > 1)
fprintf(stderr, "No scale with index %d found on this computer.\n", arguments.index);
else
fprintf(stderr, "No USB scale found on this computer.\n");
return -1;
}
@ -188,7 +250,7 @@ int main(int argc, char **argv)
// lowest bit is Enforced Zero Return, second bit is Zero Scale
unsigned char tare_report[] = {0x02, 0x02};
if (argc > 1 && strncmp(argv[1], "zero", 5) == 0) {
if (arguments.tare) {
r = libusb_interrupt_transfer(
handle,
LIBUSB_ENDPOINT_OUT + 2, // direction=host to device, type=standard, recipient=device
@ -387,17 +449,25 @@ static int print_scale_data(unsigned char* dat) {
// return the first matching `libusb_device\*` or 0 if no matching device is
// found.
//
static libusb_device* find_scale(libusb_device **devs)
static libusb_device* find_nth_scale(libusb_device **devs, int index)
{
int i = 0;
// **curr_index** counts the index of each scale, in order to find the nth
// scale as specified by **index**. Counting is 1-based, so the first scale
// has index 1.
int curr_index = 0;
libusb_device* dev = 0;
// Since each device shows up multiple times in **devs**, skip the device if
// the address is the same as the previous entry.
uint16_t last_device_address = 0;
//
// Loop through each USB device, and for each device, loop through the
// scales list to see if it's one of our listed scales.
//
while ((dev = devs[i++]) != NULL) {
struct libusb_device_descriptor desc;
int r = libusb_get_device_descriptor(dev, &desc);
if (r < 0) {
@ -406,13 +476,18 @@ static libusb_device* find_scale(libusb_device **devs)
}
int i;
for (i = 0; i < NSCALES; i++) {
if(desc.idVendor == scales[i][0] &&
desc.idProduct == scales[i][1]) {
if (is_scale(desc.idVendor, desc.idProduct)) {
// Skip this device if it's the same as the last one.
uint16_t this_device_address = (libusb_get_bus_number(dev) << 8) + libusb_get_device_address(dev);
if(this_device_address == last_device_address) {
continue;
}
last_device_address = this_device_address;
#ifdef DEBUG
/*
* Debugging data about found scale
*/
#ifdef DEBUG
fprintf(stderr,
"Found scale %04x:%04x (bus %d, device %d)\n",
desc.idVendor,
@ -420,36 +495,49 @@ static libusb_device* find_scale(libusb_device **devs)
libusb_get_bus_number(dev),
libusb_get_device_address(dev));
fprintf(stderr,
"It has descriptors:\n\tmanufc: %d\n\tprodct: %d\n\tserial: %d\n\tclass: %d\n\tsubclass: %d\n",
desc.iManufacturer,
desc.iProduct,
desc.iSerialNumber,
desc.bDeviceClass,
desc.bDeviceSubClass);
/*
* A char buffer to pull string descriptors in from the device
*/
unsigned char string[256];
libusb_device_handle* hand;
libusb_open(dev, &hand);
r = libusb_get_string_descriptor_ascii(hand, desc.iManufacturer,
string, 256);
fprintf(stderr,
"Manufacturer: %s\n", string);
libusb_close(hand);
fprintf(stderr,
"It has descriptors:\n\tmanufc: %d\n\tprodct: %d\n\tserial: %d\n\tclass: %d\n\tsubclass: %d\n",
desc.iManufacturer,
desc.iProduct,
desc.iSerialNumber,
desc.bDeviceClass,
desc.bDeviceSubClass);
/*
* A char buffer to pull string descriptors in from the device
*/
unsigned char string[256];
libusb_device_handle* hand;
libusb_open(dev, &hand);
r = libusb_get_string_descriptor_ascii(hand, desc.iManufacturer,
string, 256);
fprintf(stderr,
"Manufacturer: %s\n", string);
libusb_close(hand);
#endif
curr_index++;
if (curr_index == index) {
return dev;
break;
}
}
}
}
return NULL;
}
// **is_scale** loops through the scales list to see if the given vendor and
// product ID match any of the known USB scales.
bool is_scale(uint16_t idVendor, uint16_t idProduct) {
int i;
for (i = 0; i < NSCALES; i++) {
if(idVendor == scales[i][0] && idProduct == scales[i][1]) {
return true;
}
}
return false;
}
uint8_t get_first_endpoint_address(libusb_device* dev)
{
// default value

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