teensy3lib: do level masking instead of disable
[megadrive.git] / teensy3 / usb_mem.c
CommitLineData
35f00b6c 1/* Teensyduino Core Library
2 * http://www.pjrc.com/teensy/
3 * Copyright (c) 2013 PJRC.COM, LLC.
4 *
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:
12 *
a773ac06 13 * 1. The above copyright notice and this permission notice shall be
35f00b6c 14 * included in all copies or substantial portions of the Software.
15 *
a773ac06 16 * 2. If the Software is incorporated into a build system that allows
35f00b6c 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.
20 *
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
28 * SOFTWARE.
29 */
30
35f00b6c 31#include "usb_dev.h"
a773ac06 32#if F_CPU >= 20000000 && defined(NUM_ENDPOINTS)
33
34#include "kinetis.h"
35//#include "HardwareSerial.h"
35f00b6c 36#include "usb_mem.h"
37
38__attribute__ ((section(".usbbuffers"), used))
39unsigned char usb_buffer_memory[NUM_USB_BUFFERS * sizeof(usb_packet_t)];
40
41static uint32_t usb_buffer_available = 0xFFFFFFFF;
42
43// use bitmask and CLZ instruction to implement fast free list
44// http://www.archivum.info/gnu.gcc.help/2006-08/00148/Re-GCC-Inline-Assembly.html
45// http://gcc.gnu.org/ml/gcc/2012-06/msg00015.html
46// __builtin_clz()
47
48usb_packet_t * usb_malloc(void)
49{
50 unsigned int n, avail;
51 uint8_t *p;
52
53 __disable_irq();
54 avail = usb_buffer_available;
55 n = __builtin_clz(avail); // clz = count leading zeros
56 if (n >= NUM_USB_BUFFERS) {
57 __enable_irq();
58 return NULL;
59 }
60 //serial_print("malloc:");
61 //serial_phex(n);
62 //serial_print("\n");
63
64 usb_buffer_available = avail & ~(0x80000000 >> n);
65 __enable_irq();
66 p = usb_buffer_memory + (n * sizeof(usb_packet_t));
67 //serial_print("malloc:");
68 //serial_phex32((int)p);
69 //serial_print("\n");
70 *(uint32_t *)p = 0;
71 *(uint32_t *)(p + 4) = 0;
72 return (usb_packet_t *)p;
73}
74
75// for the receive endpoints to request memory
76extern uint8_t usb_rx_memory_needed;
77extern void usb_rx_memory(usb_packet_t *packet);
78
79void usb_free(usb_packet_t *p)
80{
81 unsigned int n, mask;
82
83 //serial_print("free:");
84 n = ((uint8_t *)p - usb_buffer_memory) / sizeof(usb_packet_t);
85 if (n >= NUM_USB_BUFFERS) return;
86 //serial_phex(n);
87 //serial_print("\n");
88
89 // if any endpoints are starving for memory to receive
90 // packets, give this memory to them immediately!
91 if (usb_rx_memory_needed && usb_configuration) {
92 //serial_print("give to rx:");
93 //serial_phex32((int)p);
94 //serial_print("\n");
95 usb_rx_memory(p);
96 return;
97 }
98
99 mask = (0x80000000 >> n);
100 __disable_irq();
101 usb_buffer_available |= mask;
102 __enable_irq();
103
104 //serial_print("free:");
105 //serial_phex32((int)p);
106 //serial_print("\n");
107}
108
a773ac06 109#endif // F_CPU >= 20 MHz && defined(NUM_ENDPOINTS)