添加一些关于midi播放的项目

2025-03-24 14:30:56 +08:00
parent e31eb22077
commit 498b4ef13b
699 changed files with 186162 additions and 1 deletions
@@ -0,0 +1,63 @@
+/****************************************************************************
+**
+** Lemcusb - Firmware USB driver for EFM32 Microcontroller
+** Copyright (C) 2014 http://lemcu.org
+**
+** This library is free software: you can redistribute it and/or modify
+** it under the terms of the GNU General Public License version 3.0 as
+** published by the Free Software Foundation and appearing in the file
+** LICENSE.txt included in the packaging of this file.
+** 
+** In addition, as a special exception, http://lemcu.org gives you certain
+** additional rights. These rights are described in the lemcu.org GPL 
+** Exception version 1.0, included in the file GPL_EXCEPTION.txt in this
+** package.
+**
+** This library is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+**
+****************************************************************************/
+
+#ifndef __USB_HELPERFUNCTIONS_H__
+#define __USB_HELPERFUNCTIONS_H__
+
+#include <stdint.h>
+
+/* from bit twiddling hacks. Did not check efficiency.
+   My guess is, that the standard assembly way using 8 consecutive ROR/ROL instructions is faster!
+so: TODO check and optimize
+*/
+static inline  uint8_t bitreverse(uint8_t b)
+{
+  return ((b * 0x0802LU & 0x22110LU) | (b * 0x8020LU & 0x88440LU)) * 0x10101LU >> 16; 
+}
+
+
+/* TODO: Make this nice and efficient! Maybe implement this directly in CM0+ assembly 
+         using uint32_t instead of uint8_t can also speed things up
+         See: http%3A%2F%2Fwww.usb.org%2Fdevelopers%2Fwhitepapers%2Fcrcdes.pdf&ei=
+              AKrAUtuBD4WMtQakyoCwAQ&usg=AFQjCNE71tY6EAUjJKXWbjtbNvDTiOKKlg&bvm=bv.
+              58187178,d.Yms&cad=rja
+ */
+static uint16_t crc16(uint16_t crc, uint8_t c)
+{
+  uint8_t  i;
+  
+  for (i=0; i<8; i++)
+  {
+    if ((crc ^ c) & 1) 
+    { 
+      crc = (crc >> 1) ^ 0xa001; /* 0xa001*/
+    } 
+    else 
+    {
+      crc >>= 1;
+    }
+    c >>= 1;
+  }
+  return crc;
+}
+
+
+#endif