Windows内核USB配置描述符解析函数

从USB配置描述符中解析相关的描述符，大量利用系统提供的函数。可以大量节省时间。

#include <usbdlib.h>

PUSB_INTERFACE_DESCRIPTOR
dsc_find_first_intf(PUSB_CONFIGURATION_DESCRIPTOR dsc_conf)
{
    return (PUSB_INTERFACE_DESCRIPTOR)USBD_ParseDescriptors(dsc_conf, dsc_conf->wTotalLength, dsc_conf, USB_INTERFACE_DESCRIPTOR_TYPE);
}

PUSB_INTERFACE_DESCRIPTOR
dsc_find_intf(PUSB_CONFIGURATION_DESCRIPTOR dsc_conf, UCHAR intf_num, USHORT alt_setting)
{
    return USBD_ParseConfigurationDescriptorEx(dsc_conf, dsc_conf, intf_num, alt_setting, -1, -1, -1);
}

static BOOLEAN
intf_has_matched_ep(PUSB_CONFIGURATION_DESCRIPTOR dsc_conf, PUSB_INTERFACE_DESCRIPTOR dsc_intf, PUSB_ENDPOINT_DESCRIPTOR dsc_ep)
{
    PVOID    start = dsc_intf;
    PUSB_ENDPOINT_DESCRIPTOR    dsc_ep_try;
    UCHAR    n_ep = dsc_intf->bNumEndpoints;

    while (n_ep > 0) {
        dsc_ep_try = dsc_next_ep(dsc_conf, start);
        if (dsc_ep_try == NULL)
            break;
        if (dsc_ep->bLength == dsc_ep_try->bLength) {
            if (RtlCompareMemory(dsc_ep, dsc_ep_try, dsc_ep->bLength) == dsc_ep->bLength)
                return TRUE;
        }
        start = dsc_ep_try;
        n_ep--;
    }
    return FALSE;
}

PUSB_INTERFACE_DESCRIPTOR
dsc_find_intf_by_ep(PUSB_CONFIGURATION_DESCRIPTOR dsc_conf, PUSB_ENDPOINT_DESCRIPTOR dsc_ep)
{
    PVOID    start = dsc_conf;

    while (start != NULL) {
        PUSB_INTERFACE_DESCRIPTOR    dsc_intf;

        dsc_intf = (PUSB_INTERFACE_DESCRIPTOR)USBD_ParseDescriptors(dsc_conf, dsc_conf->wTotalLength, start, USB_INTERFACE_DESCRIPTOR_TYPE);
        if (dsc_intf == NULL)
            break;
        if (intf_has_matched_ep(dsc_conf, dsc_intf, dsc_ep))
            return dsc_intf;
        start = NEXT_DESC(dsc_intf);
    }
    return NULL;
}

PUSB_ENDPOINT_DESCRIPTOR
dsc_find_intf_ep(PUSB_CONFIGURATION_DESCRIPTOR dsc_conf, PUSB_INTERFACE_DESCRIPTOR dsc_intf, UCHAR epaddr)
{
    PVOID    start = dsc_intf;
    PUSB_ENDPOINT_DESCRIPTOR    dsc_ep;
    int    i;

    for (i = 0; i < dsc_intf->bNumEndpoints; i++) {
        dsc_ep = dsc_next_ep(dsc_conf, start);
        if (dsc_ep == NULL)
            return NULL;
        if (dsc_ep->bEndpointAddress == epaddr)
            return dsc_ep;
    }
    return NULL;
}

PUSB_ENDPOINT_DESCRIPTOR
dsc_next_ep(PUSB_CONFIGURATION_DESCRIPTOR dsc_conf, PVOID start)
{
    PUSB_COMMON_DESCRIPTOR    dsc = (PUSB_COMMON_DESCRIPTOR)start;
    if (dsc->bDescriptorType == USB_ENDPOINT_DESCRIPTOR_TYPE)
        dsc = NEXT_DESC(dsc);
    return (PUSB_ENDPOINT_DESCRIPTOR)USBD_ParseDescriptors(dsc_conf, dsc_conf->wTotalLength, dsc, USB_ENDPOINT_DESCRIPTOR_TYPE);
}

ULONG
dsc_conf_get_n_intfs(PUSB_CONFIGURATION_DESCRIPTOR dsc_conf)
{
    PVOID    start = dsc_conf;
    ULONG    n_intfs = 0;

    while (start != NULL) {
        PUSB_COMMON_DESCRIPTOR    desc = USBD_ParseDescriptors(dsc_conf, dsc_conf->wTotalLength, start, USB_INTERFACE_DESCRIPTOR_TYPE);
        if (desc == NULL)
            break;
        start = NEXT_DESC(desc);
        n_intfs++;
    }
    return n_intfs;
}