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Further re-factor USB string handling code

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This commit refactors USB string code, making it, hopefully, less
buggy and more easier to understand. It also removes "magic" bit
manipulation and "magic" numbers;
This commit is contained in:
Andrey Smirnov 2012-11-07 11:30:44 -08:00
parent c5c4db0196
commit 720e85f850
2 changed files with 50 additions and 23 deletions
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3
include/libopencm3/usb/usbstd.h
View File

@ -220,4 +220,7 @@ struct usb_iface_assoc_descriptor {
#define USB_DT_INTERFACE_ASSOCIATION_SIZE \ #define USB_DT_INTERFACE_ASSOCIATION_SIZE \
sizeof(struct usb_iface_assoc_descriptor) sizeof(struct usb_iface_assoc_descriptor)
enum usb_language_id {
USB_LANGID_ENGLISH_US = 0x409,
};
#endif #endif

70
lib/usb/usb_standard.c
View File

@ -87,50 +87,74 @@ static u16 build_config_descriptor(u8 index, u8 *buf, u16 len)
return total; return total;
} }
static int usb_descriptor_type(u16 wValue)
{
return wValue >> 8;
}
static int usb_descriptor_index(u16 wValue)
{
return wValue & 0xFF;
}
static int usb_standard_get_descriptor(struct usb_setup_data *req, static int usb_standard_get_descriptor(struct usb_setup_data *req,
u8 **buf, u16 *len) u8 **buf, u16 *len)
{ {
int i, index; int i, array_idx, descr_idx;
struct usb_string_descriptor *sd; struct usb_string_descriptor *sd;
switch (req->wValue >> 8) { descr_idx = usb_descriptor_index(req->wValue);
switch (usb_descriptor_type(req->wValue)) {
case USB_DT_DEVICE: case USB_DT_DEVICE:
*buf = (u8 *) _usbd_device.desc; *buf = (u8 *) _usbd_device.desc;
*len = MIN(*len, _usbd_device.desc->bLength); *len = MIN(*len, _usbd_device.desc->bLength);
return 1; return USBD_REQ_HANDLED;
case USB_DT_CONFIGURATION: case USB_DT_CONFIGURATION:
*buf = _usbd_device.ctrl_buf; *buf = _usbd_device.ctrl_buf;
*len = build_config_descriptor(req->wValue & 0xff, *buf, *len); *len = build_config_descriptor(descr_idx, *buf, *len);
return 1; return USBD_REQ_HANDLED;
case USB_DT_STRING: case USB_DT_STRING:
sd = (struct usb_string_descriptor *)_usbd_device.ctrl_buf; sd = (struct usb_string_descriptor *)_usbd_device.ctrl_buf;
/* Send sane Language ID descriptor... */ if (descr_idx == 0) {
if ((req->wValue & 0xff) == 0) /* Send sane Language ID descriptor... */
sd->wData[0] = 0x409; sd->wData[0] = USB_LANGID_ENGLISH_US;
sd->bLength = sizeof(sd->bLength) + sizeof(sd->bDescriptorType)
+ sizeof(sd->wData[0]);
index = (req->wValue & 0xff) - 1; *len = MIN(*len, sd->bLength);
} else {
array_idx = descr_idx - 1;
if (!_usbd_device.strings) if (!_usbd_device.strings)
return 0; /* Device doesn't support strings. */ return USBD_REQ_NOTSUPP; /* Device doesn't support strings. */
/* Check that string index is in range. */
if (array_idx >= _usbd_device.num_strings)
return USBD_REQ_NOTSUPP;
/* Check that string index is in range. */ /* Strings with Language ID differnet from
if (index >= _usbd_device.num_strings) * USB_LANGID_ENGLISH_US are not supported */
return 0; if (req->wIndex != USB_LANGID_ENGLISH_US)
return USBD_REQ_NOTSUPP;
/* Ths string is returned as UTF16, hence the multiplication */
sd->bLength = strlen(_usbd_device.strings[array_idx]) * 2 +
sizeof(sd->bLength) + sizeof(sd->bDescriptorType);
*len = MIN(*len, sd->bLength);
for (i = 0; i < (*len / 2) - 1; i++)
sd->wData[i] =
_usbd_device.strings[array_idx][i];
}
sd->bLength = strlen(_usbd_device.strings[index]) * 2 + 2;
sd->bDescriptorType = USB_DT_STRING; sd->bDescriptorType = USB_DT_STRING;
*buf = (u8 *)sd; *buf = (u8 *)sd;
*len = MIN(*len, sd->bLength);
for (i = 0; i < (*len / 2) - 1; i++) return USBD_REQ_HANDLED;
sd->wData[i] =
_usbd_device.strings[index][i];
return 1;
} }
return 0; return USBD_REQ_NOTSUPP;
} }
static int usb_standard_set_address(struct usb_setup_data *req, u8 **buf, static int usb_standard_set_address(struct usb_setup_data *req, u8 **buf,