Fix memory alignment of USB descriptor structures.

A variety of USB descriptor structures have been manually
"unpacked". Instead of using the struct, their members were unpacked
into the struct they were nested in. Additionally sizeof()'s were
commented in favor of manual calculation of structure sizes.

After uncommenting these changes, the USB CDC peripheral stopped
correctly configuring with the host. The root problem with the
structures is that GCC is padding them. By applying
__attribute__((__packed__)), these problems are fixed. I removed all
the instances of the workaround I saw within the USB code.

Signed-off-by: RJ Ryan <rryan@mit.edu>

3 files changed, 89 insertions, 155 deletions

diff --git a/libmaple/libmaple_types.h b/libmaple/libmaple_types.h
index 17bcfb1..08adaff 100644
--- a/libmaple/libmaple_types.h
+++ b/libmaple/libmaple_types.h
@@ -47,6 +47,7 @@ typedef void (*voidFuncPtr)(void);
 
 #define __io volatile
 #define __attr_flash __attribute__((section (".USER_FLASH")))
+#define __packed __attribute__((__packed__))
 
 #ifndef NULL
 #define NULL 0
diff --git a/libmaple/usb/descriptors.c b/libmaple/usb/descriptors.c
index 8dd9521..a0bc046 100644
--- a/libmaple/usb/descriptors.c
+++ b/libmaple/usb/descriptors.c
@@ -46,32 +46,34 @@ const USB_Descriptor_Device usbVcomDescriptor_Device = {
 };
 
 const USB_Descriptor_Config usbVcomDescriptor_Config = {
- bLength:                   0x09,//sizeof(USB_Descriptor_Config_Header),
- bDescriptorType:           USB_DESCRIPTOR_TYPE_CONFIGURATION,
- wTotalLength:              0x43,//sizeof(USB_Descriptor_Config),
- bNumInterfaces:            0x02,
- bConfigurationValue:       0x01,
- iConfiguration:            0x00,
- bmAttributes:              (USB_CONFIG_ATTR_BUSPOWERED |
-                             USB_CONFIG_ATTR_SELF_POWERED),
- bMaxPower:                 USB_CONFIG_MAX_POWER,
+ Config_Header: {
+   bLength:                   sizeof(USB_Descriptor_Config_Header),
+   bDescriptorType:           USB_DESCRIPTOR_TYPE_CONFIGURATION,
+   wTotalLength:              sizeof(USB_Descriptor_Config),
+   bNumInterfaces:            0x02,
+   bConfigurationValue:       0x01,
+   iConfiguration:            0x00,
+   bmAttributes:              (USB_CONFIG_ATTR_BUSPOWERED |
+                               USB_CONFIG_ATTR_SELF_POWERED),
+   bMaxPower:                 USB_CONFIG_MAX_POWER,
+ },
 
  CCI_Interface:
    {
-   bLength:                  0x09,//sizeof(USB_Descriptor_Interface),
+   bLength:                  sizeof(USB_Descriptor_Interface),
    bDescriptorType:          USB_DESCRIPTOR_TYPE_INTERFACE,
    bInterfaceNumber:         0x00,
    bAlternateSetting:        0x00,
    bNumEndpoints:            0x01,
-   bInterfaceClass:          0x02,
-   bInterfaceSubClass:       0x02,
-   bInterfaceProtocol:       0x01,
+   bInterfaceClass:          USB_INTERFACE_CLASS_CDC,
+   bInterfaceSubClass:       USB_INTERFACE_SUBCLASS_CDC_ACM,
+   bInterfaceProtocol:       0x01, /* Common AT Commands */
    iInterface:               0x00
    },
 
  CDC_Functional_IntHeader:
    {
-   bLength:                  0x05,//sizeof(CDC_FUNCTIONAL_DESCRIPTOR(2)),
+   bLength:                  CDC_FUNCTIONAL_DESCRIPTOR_SIZE(2),
    bDescriptorType:          0x24,
    SubType:                  0x00,
    Data:                     {0x01, 0x10}
@@ -79,7 +81,7 @@ const USB_Descriptor_Config usbVcomDescriptor_Config = {
 
  CDC_Functional_CallManagement:
    {
-   bLength:                  0x05,//sizeof(CDC_FUNCTIONAL_DESCRIPTOR(2)),
+   bLength:                  CDC_FUNCTIONAL_DESCRIPTOR_SIZE(2),
    bDescriptorType:          0x24,
    SubType:                  0x01,
    Data:                     {0x03, 0x01}
@@ -87,7 +89,7 @@ const USB_Descriptor_Config usbVcomDescriptor_Config = {
 
  CDC_Functional_ACM:
    {
-   bLength:                  0x04,//sizeof(CDC_FUNCTIONAL_DESCRIPTOR(1)),
+   bLength:                  CDC_FUNCTIONAL_DESCRIPTOR_SIZE(1),
    bDescriptorType:          0x24,
    SubType:                  0x02,
    Data:                     {0x06}
@@ -95,59 +97,54 @@ const USB_Descriptor_Config usbVcomDescriptor_Config = {
 
  CDC_Functional_Union:
    {
-   bLength:                  0x05,//sizeof(CDC_FUNCTIONAL_DESCRIPTOR(2)),
+   bLength:                  CDC_FUNCTIONAL_DESCRIPTOR_SIZE(2),
    bDescriptorType:          0x24,
    SubType:                  0x06,
    Data:                     {0x00, 0x01}
    },
 
- // ManagementEndpoint:
- //  {
- EP1_bLength:                 0x07,//sizeof(USB_Descriptor_Endpoint),
- EP1_bDescriptorType:         USB_DESCRIPTOR_TYPE_ENDPOINT,
- EP1_bEndpointAddress:        (USB_DESCRIPTOR_ENDPOINT_IN | VCOM_NOTIFICATION_EPNUM),
- EP1_bmAttributes:            EP_TYPE_INTERRUPT,
- EP1_wMaxPacketSize0:         VCOM_NOTIFICATION_EPSIZE,
- EP1_wMaxPacketSize1:         0x00,
- EP1_bInterval:               0xFF,
- //  },
-
- // DCI_Interface:
- //   {
-   DCI_bLength:                0x09,//sizeof(USB_Descriptor_Interface),
-   DCI_bDescriptorType:        USB_DESCRIPTOR_TYPE_INTERFACE,
-   DCI_bInterfaceNumber:       0x01,
-   DCI_bAlternateSetting:      0x00,
-   DCI_bNumEndpoints:          0x02,
-   DCI_bInterfaceClass:        0x0A,
-   DCI_bInterfaceSubClass:     0x00,
-   DCI_bInterfaceProtocol:     0x00,
-   DCI_iInterface:             0x00,
-   //   },
-
- //DataOutEndpoint:
- // {
- //  },
- EP2_bLength:               0x07,//sizeof(USB_Descriptor_Endpoint),
- EP2_bDescriptorType:       USB_DESCRIPTOR_TYPE_ENDPOINT,
- EP2_bEndpointAddress:      (USB_DESCRIPTOR_ENDPOINT_OUT | VCOM_RX_EPNUM),
- EP2_bmAttributes:          EP_TYPE_BULK,
- EP2_wMaxPacketSize0:       VCOM_RX_EPSIZE,
- EP2_wMaxPacketSize1:       0x00,
- EP2_bInterval:             0x00,
-
-
- // DataInEndpoint:
- // {
- EP3_bLength:               0x07,//sizeof(USB_Descriptor_Endpoint),
- EP3_bDescriptorType:       USB_DESCRIPTOR_TYPE_ENDPOINT,
- EP3_bEndpointAddress:      (USB_DESCRIPTOR_ENDPOINT_IN | VCOM_TX_EPNUM),
- EP3_bmAttributes:          EP_TYPE_BULK,
- EP3_wMaxPacketSize0:       VCOM_TX_EPSIZE,
- EP3_wMaxPacketSize1:       0x00,
- EP3_bInterval:             0x00
-
- //  }
+ ManagementEndpoint:
+   {
+   bLength:                 sizeof(USB_Descriptor_Endpoint),
+   bDescriptorType:         USB_DESCRIPTOR_TYPE_ENDPOINT,
+   bEndpointAddress:        (USB_DESCRIPTOR_ENDPOINT_IN | VCOM_NOTIFICATION_EPNUM),
+   bmAttributes:            EP_TYPE_INTERRUPT,
+   wMaxPacketSize:          VCOM_NOTIFICATION_EPSIZE,
+   bInterval:               0xFF,
+   },
+
+ DCI_Interface:
+   {
+   bLength:                sizeof(USB_Descriptor_Interface),
+   bDescriptorType:        USB_DESCRIPTOR_TYPE_INTERFACE,
+   bInterfaceNumber:       0x01,
+   bAlternateSetting:      0x00,
+   bNumEndpoints:          0x02,
+   bInterfaceClass:        USB_INTERFACE_CLASS_DIC,
+   bInterfaceSubClass:     0x00, /* None */
+   bInterfaceProtocol:     0x00, /* None */
+   iInterface:             0x00,
+   },
+
+ DataOutEndpoint:
+   {
+   bLength:               sizeof(USB_Descriptor_Endpoint),
+   bDescriptorType:       USB_DESCRIPTOR_TYPE_ENDPOINT,
+   bEndpointAddress:      (USB_DESCRIPTOR_ENDPOINT_OUT | VCOM_RX_EPNUM),
+   bmAttributes:          EP_TYPE_BULK,
+   wMaxPacketSize:        VCOM_RX_EPSIZE,
+   bInterval:             0x00,
+   },
+
+ DataInEndpoint:
+   {
+   bLength:               sizeof(USB_Descriptor_Endpoint),
+   bDescriptorType:       USB_DESCRIPTOR_TYPE_ENDPOINT,
+   bEndpointAddress:      (USB_DESCRIPTOR_ENDPOINT_IN | VCOM_TX_EPNUM),
+   bmAttributes:          EP_TYPE_BULK,
+   wMaxPacketSize:        VCOM_TX_EPSIZE,
+   bInterval:             0x00
+   }
 };
 
 /*****************************************************************************
diff --git a/libmaple/usb/descriptors.h b/libmaple/usb/descriptors.h
index 460a88c..13aef29 100644
--- a/libmaple/usb/descriptors.h
+++ b/libmaple/usb/descriptors.h
@@ -37,6 +37,10 @@
 
 #define USB_DEVICE_CLASS_CDC              0x02
 #define USB_DEVICE_SUBCLASS_CDC           0x00
+#define USB_INTERFACE_CLASS_CDC           0x02
+/* CDC Abstract Control Model */
+#define USB_INTERFACE_SUBCLASS_CDC_ACM    0x02
+#define USB_INTERFACE_CLASS_DIC           0x0A
 
 #define USB_CONFIG_ATTR_BUSPOWERED        0b10000000
 #define USB_CONFIG_ATTR_SELF_POWERED      0b11000000
@@ -59,8 +63,9 @@ extern "C" {
     uint8 bLength;				\
     uint8 bDescriptorType;			\
     uint16 bString[len];			\
-  }
+  } __packed
 
+#define CDC_FUNCTIONAL_DESCRIPTOR_SIZE(DataSize) (3 + DataSize)
 #define CDC_FUNCTIONAL_DESCRIPTOR(DataSize)	\
   struct					\
   {						\
@@ -68,8 +73,9 @@ extern "C" {
     uint8 bDescriptorType;			\
     uint8 SubType;				\
     uint8 Data[DataSize];			\
-  }
+  } __packed
 
+/* See http://www.beyondlogic.org/usbnutshell/usb5.shtml#DeviceDescriptors */
 typedef struct {
   uint8                 bLength;
   uint8                 bDescriptorType;
@@ -85,8 +91,9 @@ typedef struct {
   uint8                 iProduct;
   uint8                 iSerialNumber;
   uint8                 bNumConfigurations;
-} USB_Descriptor_Device;
+} __packed USB_Descriptor_Device;
 
+/* http://www.beyondlogic.org/usbnutshell/usb5.shtml#ConfigurationDescriptors */
 typedef struct {
   uint8                 bLength;
   uint8                 bDescriptorType;
@@ -96,8 +103,9 @@ typedef struct {
   uint8                 iConfiguration;
   uint8                 bmAttributes;
   uint8                 bMaxPower;
-} USB_Descriptor_Config_Header;
+} __packed USB_Descriptor_Config_Header;
 
+/* See http://www.beyondlogic.org/usbnutshell/usb5.shtml#InterfaceDescriptors */
 typedef struct {
   uint8                 bLength;
   uint8                 bDescriptorType;
@@ -108,7 +116,8 @@ typedef struct {
   uint8                 bInterfaceSubClass;
   uint8                 bInterfaceProtocol;
   uint8                 iInterface;
-} USB_Descriptor_Interface;
+} __packed USB_Descriptor_Interface;
+
 
 typedef struct {
   uint8                 bLength;
@@ -117,99 +126,26 @@ typedef struct {
   uint8                 bmAttributes;
   uint16                wMaxPacketSize;
   uint8                 bInterval;
-} USB_Descriptor_Endpoint;
+} __packed USB_Descriptor_Endpoint;
 
 typedef struct {
-  /* config header */
-  uint8                 bLength;
-  uint8                 bDescriptorType;
-  uint16                wTotalLength;
-  uint8                 bNumInterfaces;
-  uint8                 bConfigurationValue;
-  uint8                 iConfiguration;
-  uint8                 bmAttributes;
-  uint8                 bMaxPower;
-
+  USB_Descriptor_Config_Header        Config_Header;
   USB_Descriptor_Interface            CCI_Interface;
-  struct {						
-    uint8 bLength;				
-    uint8 bDescriptorType;			
-    uint8 SubType;				
-    uint8 Data[2];			
-  }                                   CDC_Functional_IntHeader;
-  struct {						
-    uint8 bLength;				
-    uint8 bDescriptorType;			
-    uint8 SubType;				
-    uint8 Data[2];			
-  }                                   CDC_Functional_CallManagement;
-  struct {						
-    uint8 bLength;				
-    uint8 bDescriptorType;			
-    uint8 SubType;				
-    uint8 Data[1];			
-  }                                   CDC_Functional_ACM;
-  struct {						
-    uint8 bLength;				
-    uint8 bDescriptorType;			
-    uint8 SubType;				
-    uint8 Data[2];			
-  }                                   CDC_Functional_Union;
-
-  /*
+  CDC_FUNCTIONAL_DESCRIPTOR(2) CDC_Functional_IntHeader;
+  CDC_FUNCTIONAL_DESCRIPTOR(2) CDC_Functional_CallManagement;
+  CDC_FUNCTIONAL_DESCRIPTOR(1) CDC_Functional_ACM;
+  CDC_FUNCTIONAL_DESCRIPTOR(2) CDC_Functional_Union;
   USB_Descriptor_Endpoint             ManagementEndpoint;
-  */
-  uint8                 EP1_bLength;
-  uint8                 EP1_bDescriptorType;
-  uint8                 EP1_bEndpointAddress;
-  uint8                 EP1_bmAttributes;
-  uint8                 EP1_wMaxPacketSize0;
-  uint8                 EP1_wMaxPacketSize1;
-  uint8                 EP1_bInterval;
-
-  /*
   USB_Descriptor_Interface            DCI_Interface;
-  */
-
-  uint8                 DCI_bLength;
-  uint8                 DCI_bDescriptorType;
-  uint8                 DCI_bInterfaceNumber;
-  uint8                 DCI_bAlternateSetting;
-  uint8                 DCI_bNumEndpoints;
-  uint8                 DCI_bInterfaceClass;
-  uint8                 DCI_bInterfaceSubClass;
-  uint8                 DCI_bInterfaceProtocol;
-  uint8                 DCI_iInterface;
-
-  /*
   USB_Descriptor_Endpoint             DataOutEndpoint;
   USB_Descriptor_Endpoint             DataInEndpoint;
-  */
-
-  uint8                 EP2_bLength;
-  uint8                 EP2_bDescriptorType;
-  uint8                 EP2_bEndpointAddress;
-  uint8                 EP2_bmAttributes;
-  uint8                 EP2_wMaxPacketSize0;
-  uint8                 EP2_wMaxPacketSize1;
-  uint8                 EP2_bInterval;
-
-  uint8                 EP3_bLength;
-  uint8                 EP3_bDescriptorType;
-  uint8                 EP3_bEndpointAddress;
-  uint8                 EP3_bmAttributes;
-  uint8                 EP3_wMaxPacketSize0;
-  uint8                 EP3_wMaxPacketSize1;
-  uint8                 EP3_bInterval;
-
-  
-}USB_Descriptor_Config;
- 
-  typedef struct {
-    uint8          bLength;
-    uint8          bDescriptorType;
-    uint16         bString[];
-  } USB_Descriptor_String;
+} __packed USB_Descriptor_Config;
+
+typedef struct {
+  uint8          bLength;
+  uint8          bDescriptorType;
+  uint16         bString[];
+} USB_Descriptor_String;
 
 extern const USB_Descriptor_Device usbVcomDescriptor_Device;
 extern const USB_Descriptor_Config usbVcomDescriptor_Config;