1 /* Teensyduino Core Library
2 * http://www.pjrc.com/teensy/
3 * Copyright (c) 2013 PJRC.COM, LLC.
5 * Permission is hereby granted, free of charge, to any person obtaining
6 * a copy of this software and associated documentation files (the
7 * "Software"), to deal in the Software without restriction, including
8 * without limitation the rights to use, copy, modify, merge, publish,
9 * distribute, sublicense, and/or sell copies of the Software, and to
10 * permit persons to whom the Software is furnished to do so, subject to
11 * the following conditions:
13 * 1. The above copyright notice and this permission notice shall be
14 * included in all copies or substantial portions of the Software.
16 * 2. If the Software is incorporated into a build system that allows
17 * selection among a list of target devices, then similar target
18 * devices manufactured by PJRC.COM must be included in the list of
19 * target devices and selectable in the same manner.
21 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
22 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
23 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
24 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
25 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
26 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
27 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
31 #include "mk20dx128.h"
32 //#include "HardwareSerial.h"
36 __attribute__ ((section(".usbbuffers"), used))
37 unsigned char usb_buffer_memory[NUM_USB_BUFFERS * sizeof(usb_packet_t)];
39 static uint32_t usb_buffer_available = 0xFFFFFFFF;
41 // use bitmask and CLZ instruction to implement fast free list
42 // http://www.archivum.info/gnu.gcc.help/2006-08/00148/Re-GCC-Inline-Assembly.html
43 // http://gcc.gnu.org/ml/gcc/2012-06/msg00015.html
46 usb_packet_t * usb_malloc(void)
48 unsigned int n, avail;
52 avail = usb_buffer_available;
53 n = __builtin_clz(avail); // clz = count leading zeros
54 if (n >= NUM_USB_BUFFERS) {
58 //serial_print("malloc:");
62 usb_buffer_available = avail & ~(0x80000000 >> n);
64 p = usb_buffer_memory + (n * sizeof(usb_packet_t));
65 //serial_print("malloc:");
66 //serial_phex32((int)p);
69 *(uint32_t *)(p + 4) = 0;
70 return (usb_packet_t *)p;
73 // for the receive endpoints to request memory
74 extern uint8_t usb_rx_memory_needed;
75 extern void usb_rx_memory(usb_packet_t *packet);
77 void usb_free(usb_packet_t *p)
81 //serial_print("free:");
82 n = ((uint8_t *)p - usb_buffer_memory) / sizeof(usb_packet_t);
83 if (n >= NUM_USB_BUFFERS) return;
87 // if any endpoints are starving for memory to receive
88 // packets, give this memory to them immediately!
89 if (usb_rx_memory_needed && usb_configuration) {
90 //serial_print("give to rx:");
91 //serial_phex32((int)p);
97 mask = (0x80000000 >> n);
99 usb_buffer_available |= mask;
102 //serial_print("free:");
103 //serial_phex32((int)p);
104 //serial_print("\n");