Add double buffering routines

Signed-off-by: Manuel Odendahl <wesen@ruinwesen.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/libmaple/usb/stm32f1/usb_reg_map.c b/libmaple/usb/stm32f1/usb_reg_map.c
index 75562e1..fbfca86 100644
--- a/libmaple/usb/stm32f1/usb_reg_map.c
+++ b/libmaple/usb/stm32f1/usb_reg_map.c
@@ -58,6 +58,26 @@ void usb_copy_from_pma(uint8 *buf, uint16 len, uint16 pma_offset) {
     }
 }
 
+void usb_set_ep_rx_buf0_count(uint8 ep, uint16 count) {
+    uint32 *rxc = usb_ep_tx_count_ptr(ep);
+    uint16 nblocks;
+    if (count > 62) {
+        /* use 32-byte memory block size */
+        nblocks = count >> 5;
+        if ((count & 0x1F) == 0) {
+            nblocks--;
+        }
+        *rxc = (nblocks << 10) | 0x8000;
+    } else {
+        /* use 2-byte memory block size */
+        nblocks = count >> 1;
+        if ((count & 0x1) != 0) {
+            nblocks++;
+        }
+        *rxc = nblocks << 10;
+    }
+}
+
 void usb_set_ep_rx_count(uint8 ep, uint16 count) {
     uint32 *rxc = usb_ep_rx_count_ptr(ep);
     uint16 nblocks;