Attempt to add availableForWrite() to USB Serial

Author: rogerclarkmelbourne

STM32F1/cores/maple/libmaple/usb/stm32f1/usb_cdcacm.c

@@ -456,6 +456,11 @@ uint8 usb_cdcacm_is_transmitting(void) {
     return ( transmitting>0 ? transmitting : 0);
 }
 
+int usb_cdcacm_tx_available()
+{
+	return CDC_SERIAL_TX_BUFFER_SIZE - usb_cdcacm_get_pending();
+}
+
 uint16 usb_cdcacm_get_pending(void) {
     return (tx_head - tx_tail) & CDC_SERIAL_TX_BUFFER_SIZE_MASK;
 }

STM32F1/cores/maple/usb_serial.cpp

@@ -148,6 +148,8 @@ int USBSerial::peek(void)
 	}
 }
 
+int USBSerial::availableForWrite(void) { return usb_cdcacm_tx_available(); }
+
 void USBSerial::flush(void)
 {
 /*Roger Clark. Rather slow method. Need to improve this */

STM32F1/system/libmaple/include/libmaple/usb_cdcacm.h

@@ -129,10 +129,13 @@ uint32 usb_cdcacm_peek_ex(uint8* buf, uint32 offset, uint32 len);
 uint32 usb_cdcacm_data_available(void); /* in RX buffer */
 uint16 usb_cdcacm_get_pending(void);
 uint8 usb_cdcacm_is_transmitting(void);
+int usb_cdcacm_tx_available();
 
 uint8 usb_cdcacm_get_dtr(void);
 uint8 usb_cdcacm_get_rts(void);
 
+
+
 typedef struct usb_cdcacm_line_coding {
     uint32 dwDTERate;           /* Baud rate */