Add 'teensytp/' from commit 'be48e888050f18a31e788269c8f47358036a8e3b'

[megadrive.git] / teensytp / teensy3 / usb_mem.c

diff --git a/teensytp/teensy3/usb_mem.c b/teensytp/teensy3/usb_mem.c
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+++ b/teensytp/teensy3/usb_mem.c
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+/* Teensyduino Core Library
+ * http://www.pjrc.com/teensy/
+ * Copyright (c) 2013 PJRC.COM, LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * 1. The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * 2. If the Software is incorporated into a build system that allows
+ * selection among a list of target devices, then similar target
+ * devices manufactured by PJRC.COM must be included in the list of
+ * target devices and selectable in the same manner.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "usb_dev.h"
+#if F_CPU >= 20000000 && defined(NUM_ENDPOINTS)
+
+#include "kinetis.h"
+//#include "HardwareSerial.h"
+#include "usb_mem.h"
+
+__attribute__ ((section(".usbbuffers"), used))
+unsigned char usb_buffer_memory[NUM_USB_BUFFERS * sizeof(usb_packet_t)];
+
+static uint32_t usb_buffer_available = 0xFFFFFFFF;
+
+// use bitmask and CLZ instruction to implement fast free list
+// http://www.archivum.info/gnu.gcc.help/2006-08/00148/Re-GCC-Inline-Assembly.html
+// http://gcc.gnu.org/ml/gcc/2012-06/msg00015.html
+// __builtin_clz()
+
+usb_packet_t * usb_malloc(void)
+{
+       unsigned int n, avail, avail_new;
+       uint8_t *p;
+
+       do {
+               avail = usb_buffer_available;
+               n = __builtin_clz(avail); // clz = count leading zeros
+               if (n >= NUM_USB_BUFFERS) return NULL;
+
+               //serial_print("malloc:");
+               //serial_phex(n);
+               //serial_print("\n");
+
+               avail_new = avail & ~(0x80000000 >> n);
+       }
+       while (!__sync_bool_compare_and_swap(&usb_buffer_available, avail, avail_new));
+
+       p = usb_buffer_memory + (n * sizeof(usb_packet_t));
+       //serial_print("malloc:");
+       //serial_phex32((int)p);
+       //serial_print("\n");
+       *(uint32_t *)p = 0;
+       *(uint32_t *)(p + 4) = 0;
+       return (usb_packet_t *)p;
+}
+
+// for the receive endpoints to request memory
+extern uint8_t usb_rx_memory_needed;
+extern void usb_rx_memory(usb_packet_t *packet);
+
+void usb_free(usb_packet_t *p)
+{
+       unsigned int n, mask;
+
+       //serial_print("free:");
+       n = ((uint8_t *)p - usb_buffer_memory) / sizeof(usb_packet_t);
+       if (n >= NUM_USB_BUFFERS) return;
+       //serial_phex(n);
+       //serial_print("\n");
+
+       // if any endpoints are starving for memory to receive
+       // packets, give this memory to them immediately!
+       if (usb_rx_memory_needed && usb_configuration) {
+               //serial_print("give to rx:");
+               //serial_phex32((int)p);
+               //serial_print("\n");
+               usb_rx_memory(p);
+               return;
+       }
+
+       mask = (0x80000000 >> n);
+       __sync_fetch_and_or(&usb_buffer_available, mask);
+
+       //serial_print("free:");
+       //serial_phex32((int)p);
+       //serial_print("\n");
+}
+
+#endif // F_CPU >= 20 MHz && defined(NUM_ENDPOINTS)