From ef16109c5dbde3136ae901b55525eb59f1d1fb4f Mon Sep 17 00:00:00 2001
From: sommersoft <sommersoft@gmail.com>
Date: Sat, 24 Mar 2018 00:55:48 +0000
Subject: [PATCH] updated with requested changes

---
 ports/atmel-samd/usb.c | 28 +++++++---------------------
 1 file changed, 7 insertions(+), 21 deletions(-)

diff --git a/ports/atmel-samd/usb.c b/ports/atmel-samd/usb.c
index 6148c56ae6..af70be99af 100644
--- a/ports/atmel-samd/usb.c
+++ b/ports/atmel-samd/usb.c
@@ -102,12 +102,13 @@ static void init_hardware(void) {
     #endif
 }
 
-COMPILER_ALIGNED(4) uint8_t cdc_packet_buffer[64];
+#define CDC_BULKOUT_SIZE CONF_USB_COMPOSITE_CDC_ACM_DATA_BULKOUT_MAXPKSZ
+COMPILER_ALIGNED(4) uint8_t cdc_packet_buffer[CDC_BULKOUT_SIZE];
 static volatile bool pending_read;
 
 static int32_t start_read(void) {
     pending_read = true;
-    int32_t result = cdcdf_acm_read(cdc_packet_buffer, 64);
+    int32_t result = cdcdf_acm_read(cdc_packet_buffer, CDC_BULKOUT_SIZE);
     if (result != ERR_NONE) {
         pending_read = false;
     }
@@ -151,14 +152,6 @@ static bool read_complete(const uint8_t ep, const enum usb_xfer_code rc, const u
     }
     atomic_leave_critical(&flags);
 
-    // Trigger a follow up read if we have space.
-    /*if (usb_rx_count < USB_RX_BUF_SIZE - 64) {
-        int32_t result = start_read();
-        if (result != ERR_NONE) {
-            return true;
-        }
-    }*/
-
     /* No error. */
     return false;
 }
@@ -247,7 +240,7 @@ static bool cdc_enabled(void) {
 bool usb_bytes_available(void) {
     // Check if the buffer has data, but not enough
     // space to hold another read.
-    if (usb_rx_count > 64) {
+    if (usb_rx_count > CDC_BULKOUT_SIZE) {
         return usb_rx_count > 0;
     }
     // Buffer has enough room
@@ -277,11 +270,6 @@ int usb_read(void) {
     }
     CRITICAL_SECTION_LEAVE();
 
-    // Trigger a new read because we just cleared some space.
-    /*if (!pending_read && usb_rx_count == USB_RX_BUF_SIZE - 1) {
-        start_read();
-    }*/
-
     return data;
 }
 
@@ -328,12 +316,10 @@ bool usb_connected(void) {
 
 // Poll for input if keyboard interrupts are enabled,
 // so that we can check for the interrupt char. read_complete() does the checking.
+// also make sure we have enough room in the local buffer
 void usb_cdc_background() {
     //
-    if (mp_interrupt_char != -1 && cdc_enabled() && !pending_read) {
-        // Make sure we have space in the buffer
-        if (usb_rx_count < 64) {
-            start_read();
-        }        
+    if (mp_interrupt_char != -1 && cdc_enabled() && !pending_read && usb_rx_count < CDC_BULKOUT_SIZE) {
+        start_read();
     }
 }