From 4ba8614c006f9828f0796c140bc3e13c9e67938c Mon Sep 17 00:00:00 2001 From: Yuval Adam Date: Mon, 29 Oct 2012 23:06:01 +0200 Subject: Added utils --- utils/crc.c | 756 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 756 insertions(+) create mode 100644 utils/crc.c (limited to 'utils/crc.c') diff --git a/utils/crc.c b/utils/crc.c new file mode 100644 index 0000000..cf60e81 --- /dev/null +++ b/utils/crc.c @@ -0,0 +1,756 @@ +//***************************************************************************** +// +// crc.c - CRC functions. +// +// Copyright (c) 2010-2012 Texas Instruments Incorporated. All rights reserved. +// Software License Agreement +// +// Texas Instruments (TI) is supplying this software for use solely and +// exclusively on TI's microcontroller products. The software is owned by +// TI and/or its suppliers, and is protected under applicable copyright +// laws. You may not combine this software with "viral" open-source +// software in order to form a larger program. +// +// THIS SOFTWARE IS PROVIDED "AS IS" AND WITH ALL FAULTS. +// NO WARRANTIES, WHETHER EXPRESS, IMPLIED OR STATUTORY, INCLUDING, BUT +// NOT LIMITED TO, IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE APPLY TO THIS SOFTWARE. TI SHALL NOT, UNDER ANY +// CIRCUMSTANCES, BE LIABLE FOR SPECIAL, INCIDENTAL, OR CONSEQUENTIAL +// DAMAGES, FOR ANY REASON WHATSOEVER. +// +// This is part of revision 9453 of the Stellaris Firmware Development Package. +// +//***************************************************************************** + +//***************************************************************************** +// +//! \addtogroup crc_api +//! @{ +// +//***************************************************************************** + +#include "crc.h" + +//***************************************************************************** +// +// The CRC table for the polynomial C(x) = x^8 + x^2 + x + 1 (CRC-8-CCITT). +// +//***************************************************************************** +static const unsigned char g_pucCrc8CCITT[256] = +{ + 0x00, 0x07, 0x0E, 0x09, 0x1C, 0x1B, 0x12, 0x15, + 0x38, 0x3F, 0x36, 0x31, 0x24, 0x23, 0x2A, 0x2D, + 0x70, 0x77, 0x7E, 0x79, 0x6C, 0x6B, 0x62, 0x65, + 0x48, 0x4F, 0x46, 0x41, 0x54, 0x53, 0x5A, 0x5D, + 0xE0, 0xE7, 0xEE, 0xE9, 0xFC, 0xFB, 0xF2, 0xF5, + 0xD8, 0xDF, 0xD6, 0xD1, 0xC4, 0xC3, 0xCA, 0xCD, + 0x90, 0x97, 0x9E, 0x99, 0x8C, 0x8B, 0x82, 0x85, + 0xA8, 0xAF, 0xA6, 0xA1, 0xB4, 0xB3, 0xBA, 0xBD, + 0xC7, 0xC0, 0xC9, 0xCE, 0xDB, 0xDC, 0xD5, 0xD2, + 0xFF, 0xF8, 0xF1, 0xF6, 0xE3, 0xE4, 0xED, 0xEA, + 0xB7, 0xB0, 0xB9, 0xBE, 0xAB, 0xAC, 0xA5, 0xA2, + 0x8F, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9D, 0x9A, + 0x27, 0x20, 0x29, 0x2E, 0x3B, 0x3C, 0x35, 0x32, + 0x1F, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0D, 0x0A, + 0x57, 0x50, 0x59, 0x5E, 0x4B, 0x4C, 0x45, 0x42, + 0x6F, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7D, 0x7A, + 0x89, 0x8E, 0x87, 0x80, 0x95, 0x92, 0x9B, 0x9C, + 0xB1, 0xB6, 0xBF, 0xB8, 0xAD, 0xAA, 0xA3, 0xA4, + 0xF9, 0xFE, 0xF7, 0xF0, 0xE5, 0xE2, 0xEB, 0xEC, + 0xC1, 0xC6, 0xCF, 0xC8, 0xDD, 0xDA, 0xD3, 0xD4, + 0x69, 0x6E, 0x67, 0x60, 0x75, 0x72, 0x7B, 0x7C, + 0x51, 0x56, 0x5F, 0x58, 0x4D, 0x4A, 0x43, 0x44, + 0x19, 0x1E, 0x17, 0x10, 0x05, 0x02, 0x0B, 0x0C, + 0x21, 0x26, 0x2F, 0x28, 0x3D, 0x3A, 0x33, 0x34, + 0x4E, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5C, 0x5B, + 0x76, 0x71, 0x78, 0x7F, 0x6A, 0x6D, 0x64, 0x63, + 0x3E, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2C, 0x2B, + 0x06, 0x01, 0x08, 0x0F, 0x1A, 0x1D, 0x14, 0x13, + 0xAE, 0xA9, 0xA0, 0xA7, 0xB2, 0xB5, 0xBC, 0xBB, + 0x96, 0x91, 0x98, 0x9F, 0x8A, 0x8D, 0x84, 0x83, + 0xDE, 0xD9, 0xD0, 0xD7, 0xC2, 0xC5, 0xCC, 0xCB, + 0xE6, 0xE1, 0xE8, 0xEF, 0xFA, 0xFD, 0xF4, 0xF3 +}; + +//***************************************************************************** +// +// The CRC-16 table for the polynomial C(x) = x^16 + x^15 + x^2 + 1 (standard +// CRC-16, also known as CRC-16-IBM and CRC-16-ANSI). +// +//***************************************************************************** +static const unsigned short g_pusCrc16[256] = +{ + 0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241, + 0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440, + 0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40, + 0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841, + 0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40, + 0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41, + 0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641, + 0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040, + 0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240, + 0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441, + 0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41, + 0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840, + 0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41, + 0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40, + 0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640, + 0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041, + 0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240, + 0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441, + 0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41, + 0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840, + 0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41, + 0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40, + 0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640, + 0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041, + 0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241, + 0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440, + 0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40, + 0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841, + 0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40, + 0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41, + 0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641, + 0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040 +}; + +//***************************************************************************** +// +// The CRC-32 table for the polynomial C(x) = x^32 + x^26 + x^23 + x^22 + +// x^16 + x^12 + x^11 + x^10 + x^8 + x^7 + x^5 + x^4 + x^2 + x + 1 (standard +// CRC32 as used in Ethernet, MPEG-2, PNG, etc.). +// +//***************************************************************************** +const unsigned long g_pulCrc32[] = +{ + 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, + 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3, + 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, + 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, + 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, + 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, + 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, + 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5, + 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, + 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, + 0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, + 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59, + 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, + 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f, + 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, + 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, + 0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, + 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433, + 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, + 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01, + 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, + 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, + 0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, + 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65, + 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, + 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, + 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, + 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, + 0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, + 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f, + 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, + 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, + 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, + 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, + 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, + 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, + 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, + 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7, + 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, + 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, + 0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, + 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b, + 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, + 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79, + 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, + 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, + 0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, + 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d, + 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, + 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713, + 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, + 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, + 0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, + 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777, + 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, + 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, + 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, + 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, + 0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, + 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9, + 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, + 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf, + 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, + 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d, +}; + +//***************************************************************************** +// +// This macro executes one iteration of the CRC-8-CCITT. +// +//***************************************************************************** +#define CRC8_ITER(crc, data) g_pucCrc8CCITT[(unsigned char)((crc) ^ (data))] + +//***************************************************************************** +// +// This macro executes one iteration of the CRC-16. +// +//***************************************************************************** +#define CRC16_ITER(crc, data) (((crc) >> 8) ^ \ + g_pusCrc16[(unsigned char)((crc) ^ (data))]) + +//***************************************************************************** +// +// This macro executes one iteration of the CRC-32. +// +//***************************************************************************** +#define CRC32_ITER(crc, data) (((crc) >> 8) ^ \ + g_pulCrc32[(unsigned char)((crc & 0xFF) ^ \ + (data))]) + +//***************************************************************************** +// +//! Calculates the CRC-8-CCITT of an array of bytes. +//! +//! \param ucCrc is the starting CRC-8-CCITT value. +//! \param pucData is a pointer to the data buffer. +//! \param ulCount is the number of bytes in the data buffer. +//! +//! This function is used to calculate the CRC-8-CCITT of the input buffer. +//! The CRC-8-CCITT is computed in a running fashion, meaning that the entire +//! data block that is to have its CRC-8-CCITT computed does not need to be +//! supplied all at once. If the input buffer contains the entire block of +//! data, then \b ucCrc should be set to 0. If, however, the entire block of +//! data is not available, then \b ucCrc should be set to 0 for the first +//! portion of the data, and then the returned value should be passed back in +//! as \b ucCrc for the next portion of the data. +//! +//! For example, to compute the CRC-8-CCITT of a block that has been split into +//! three pieces, use the following: +//! +//! \verbatim +//! ucCrc = Crc8CCITT(0, pucData1, ulLen1); +//! ucCrc = Crc8CCITT(ucCrc, pucData2, ulLen2); +//! ucCrc = Crc8CCITT(ucCrc, pucData3, ulLen3); +//! \endverbatim +//! +//! Computing a CRC-8-CCITT in a running fashion is useful in cases where the +//! data is arriving via a serial link (for example) and is therefore not all +//! available at one time. +//! +//! \return The CRC-8-CCITT of the input data. +// +//***************************************************************************** +unsigned char +Crc8CCITT(unsigned char ucCrc, const unsigned char *pucData, + unsigned long ulCount) +{ + unsigned long ulTemp; + + // + // If the data buffer is not short-aligned, then perform a single step of + // the CRC to make it short-aligned. + // + if((unsigned long)pucData & 1) + { + // + // Perform the CRC on this input byte. + // + ucCrc = CRC8_ITER(ucCrc, *pucData); + + // + // Skip this input byte. + // + pucData++; + ulCount--; + } + + // + // If the data buffer is not word-aligned and there are at least two bytes + // of data left, then perform two steps of the CRC to make it word-aligned. + // + if(((unsigned long)pucData & 2) && (ulCount > 1)) + { + // + // Read the next short. + // + ulTemp = *(unsigned short *)pucData; + + // + // Perform the CRC on these two bytes. + // + ucCrc = CRC8_ITER(ucCrc, ulTemp); + ucCrc = CRC8_ITER(ucCrc, ulTemp >> 8); + + // + // Skip these input bytes. + // + pucData += 2; + ulCount -= 2; + } + + // + // While there is at least a word remaining in the data buffer, perform + // four steps of the CRC to consume a word. + // + while(ulCount > 3) + { + // + // Read the next word. + // + ulTemp = *(unsigned long *)pucData; + + // + // Perform the CRC on these four bytes. + // + ucCrc = CRC8_ITER(ucCrc, ulTemp); + ucCrc = CRC8_ITER(ucCrc, ulTemp >> 8); + ucCrc = CRC8_ITER(ucCrc, ulTemp >> 16); + ucCrc = CRC8_ITER(ucCrc, ulTemp >> 24); + + // + // Skip these input bytes. + // + pucData += 4; + ulCount -= 4; + } + + // + // If there is a short left in the input buffer, then perform two steps of + // the CRC. + // + if(ulCount > 1) + { + // + // Read the short. + // + ulTemp = *(unsigned short *)pucData; + + // + // Perform the CRC on these two bytes. + // + ucCrc = CRC8_ITER(ucCrc, ulTemp); + ucCrc = CRC8_ITER(ucCrc, ulTemp >> 8); + + // + // Skip these input bytes. + // + pucData += 2; + ulCount -= 2; + } + + // + // If there is a final byte remaining in the input buffer, then perform a + // single step of the CRC. + // + if(ulCount != 0) + { + ucCrc = CRC8_ITER(ucCrc, *pucData); + } + + // + // Return the resulting CRC-8-CCITT value. + // + return(ucCrc); +} + +//***************************************************************************** +// +//! Calculates the CRC-16 of an array of bytes. +//! +//! \param usCrc is the starting CRC-16 value. +//! \param pucData is a pointer to the data buffer. +//! \param ulCount is the number of bytes in the data buffer. +//! +//! This function is used to calculate the CRC-16 of the input buffer. The +//! CRC-16 is computed in a running fashion, meaning that the entire data block +//! that is to have its CRC-16 computed does not need to be supplied all at +//! once. If the input buffer contains the entire block of data, then \b usCrc +//! should be set to 0. If, however, the entire block of data is not +//! available, then \b usCrc should be set to 0 for the first portion of the +//! data, and then the returned value should be passed back in as \b usCrc for +//! the next portion of the data. +//! +//! For example, to compute the CRC-16 of a block that has been split into +//! three pieces, use the following: +//! +//! \verbatim +//! usCrc = Crc16(0, pucData1, ulLen1); +//! usCrc = Crc16(usCrc, pucData2, ulLen2); +//! usCrc = Crc16(usCrc, pucData3, ulLen3); +//! \endverbatim +//! +//! Computing a CRC-16 in a running fashion is useful in cases where the data +//! is arriving via a serial link (for example) and is therefore not all +//! available at one time. +//! +//! \return The CRC-16 of the input data. +// +//***************************************************************************** +unsigned short +Crc16(unsigned short usCrc, const unsigned char *pucData, + unsigned long ulCount) +{ + unsigned long ulTemp; + + // + // If the data buffer is not short-aligned, then perform a single step of + // the CRC to make it short-aligned. + // + if((unsigned long)pucData & 1) + { + // + // Perform the CRC on this input byte. + // + usCrc = CRC16_ITER(usCrc, *pucData); + + // + // Skip this input byte. + // + pucData++; + ulCount--; + } + + // + // If the data buffer is not word-aligned and there are at least two bytes + // of data left, then perform two steps of the CRC to make it word-aligned. + // + if(((unsigned long)pucData & 2) && (ulCount > 1)) + { + // + // Read the next short. + // + ulTemp = *(unsigned short *)pucData; + + // + // Perform the CRC on these two bytes. + // + usCrc = CRC16_ITER(usCrc, ulTemp); + usCrc = CRC16_ITER(usCrc, ulTemp >> 8); + + // + // Skip these input bytes. + // + pucData += 2; + ulCount -= 2; + } + + // + // While there is at least a word remaining in the data buffer, perform + // four steps of the CRC to consume a word. + // + while(ulCount > 3) + { + // + // Read the next word. + // + ulTemp = *(unsigned long *)pucData; + + // + // Perform the CRC on these four bytes. + // + usCrc = CRC16_ITER(usCrc, ulTemp); + usCrc = CRC16_ITER(usCrc, ulTemp >> 8); + usCrc = CRC16_ITER(usCrc, ulTemp >> 16); + usCrc = CRC16_ITER(usCrc, ulTemp >> 24); + + // + // Skip these input bytes. + // + pucData += 4; + ulCount -= 4; + } + + // + // If there is a short left in the input buffer, then perform two steps of + // the CRC. + // + if(ulCount > 1) + { + // + // Read the short. + // + ulTemp = *(unsigned short *)pucData; + + // + // Perform the CRC on these two bytes. + // + usCrc = CRC16_ITER(usCrc, ulTemp); + usCrc = CRC16_ITER(usCrc, ulTemp >> 8); + + // + // Skip these input bytes. + // + pucData += 2; + ulCount -= 2; + } + + // + // If there is a final byte remaining in the input buffer, then perform a + // single step of the CRC. + // + if(ulCount != 0) + { + usCrc = CRC16_ITER(usCrc, *pucData); + } + + // + // Return the resulting CRC-16 value. + // + return(usCrc); +} + +//***************************************************************************** +// +//! Calculates the CRC-16 of an array of words. +//! +//! \param ulWordLen is the length of the array in words (the number of bytes +//! divided by 4). +//! \param pulData is a pointer to the data buffer. +//! +//! This function is a wrapper around the running CRC-16 function, providing +//! the CRC-16 for a single block of data. +//! +//! \return The CRC-16 of the input data. +// +//***************************************************************************** +unsigned short +Crc16Array(unsigned long ulWordLen, const unsigned long *pulData) +{ + // + // Calculate and return the CRC-16 of this array of words. + // + return(Crc16(0, (const unsigned char *)pulData, ulWordLen * 4)); +} + +//***************************************************************************** +// +//! Calculates three CRC-16s of an array of words. +//! +//! \param ulWordLen is the length of the array in words (the number of bytes +//! divided by 4). +//! \param pulData is a pointer to the data buffer. +//! \param pusCrc3 is a pointer to an array in which to place the three CRC-16 +//! values. +//! +//! This function is used to calculate three CRC-16s of the input buffer; the +//! first uses every byte from the array, the second uses only the even-index +//! bytes from the array (in other words, bytes 0, 2, 4, etc.), and the third +//! uses only the odd-index bytes from the array (in other words, bytes 1, 3, +//! 5, etc.). +//! +//! \return None +// +//***************************************************************************** +void +Crc16Array3(unsigned long ulWordLen, const unsigned long *pulData, + unsigned short *pusCrc3) +{ + unsigned short usCrc, usCrcOdd, usCrcEven; + unsigned long ulTemp; + + // + // Initialize the CRC values to zero. + // + usCrc = 0; + usCrcOdd = 0; + usCrcEven = 0; + + // + // Loop while there are more words in the data buffer. + // + while(ulWordLen--) + { + // + // Read the next word. + // + ulTemp = *pulData++; + + // + // Perform the first CRC on all four data bytes. + // + usCrc = CRC16_ITER(usCrc, ulTemp); + usCrc = CRC16_ITER(usCrc, ulTemp >> 8); + usCrc = CRC16_ITER(usCrc, ulTemp >> 16); + usCrc = CRC16_ITER(usCrc, ulTemp >> 24); + + // + // Perform the second CRC on only the even-index data bytes. + // + usCrcEven = CRC16_ITER(usCrcEven, ulTemp); + usCrcEven = CRC16_ITER(usCrcEven, ulTemp >> 16); + + // + // Perform the third CRC on only the odd-index data bytes. + // + usCrcOdd = CRC16_ITER(usCrcOdd, ulTemp >> 8); + usCrcOdd = CRC16_ITER(usCrcOdd, ulTemp >> 24); + } + + // + // Return the resulting CRC-16 values. + // + pusCrc3[0] = usCrc; + pusCrc3[1] = usCrcEven; + pusCrc3[2] = usCrcOdd; +} + +//***************************************************************************** +// +//! Calculates the CRC-32 of an array of bytes. +//! +//! \param ulCrc is the starting CRC-32 value. +//! \param pucData is a pointer to the data buffer. +//! \param ulCount is the number of bytes in the data buffer. +//! +//! This function is used to calculate the CRC-32 of the input buffer. The +//! CRC-32 is computed in a running fashion, meaning that the entire data block +//! that is to have its CRC-32 computed does not need to be supplied all at +//! once. If the input buffer contains the entire block of data, then \b ulCrc +//! should be set to 0xFFFFFFFF. If, however, the entire block of data is not +//! available, then \b ulCrc should be set to 0xFFFFFFFF for the first portion +//! of the data, and then the returned value should be passed back in as \b +//! ulCrc for the next portion of the data. Once all data has been passed +//! to the function, the final CRC-32 can be obtained by inverting the last +//! returned value. +//! +//! For example, to compute the CRC-32 of a block that has been split into +//! three pieces, use the following: +//! +//! \verbatim +//! ulCrc = Crc32(0xFFFFFFFF, pucData1, ulLen1); +//! ulCrc = Crc32(ulCrc, pucData2, ulLen2); +//! ulCrc = Crc32(ulCrc, pucData3, ulLen3); +//! ulCrc ^= 0xFFFFFFFF; +//! \endverbatim +//! +//! Computing a CRC-32 in a running fashion is useful in cases where the data +//! is arriving via a serial link (for example) and is therefore not all +//! available at one time. +//! +//! \return The accumulated CRC-32 of the input data. +// +//***************************************************************************** +unsigned long +Crc32(unsigned long ulCrc, const unsigned char *pucData, unsigned long ulCount) +{ + unsigned long ulTemp; + + // + // If the data buffer is not short-aligned, then perform a single step of + // the CRC to make it short-aligned. + // + if((unsigned long)pucData & 1) + { + // + // Perform the CRC on this input byte. + // + ulCrc = CRC32_ITER(ulCrc, *pucData); + + // + // Skip this input byte. + // + pucData++; + ulCount--; + } + + // + // If the data buffer is not word-aligned and there are at least two bytes + // of data left, then perform two steps of the CRC to make it word-aligned. + // + if(((unsigned long)pucData & 2) && (ulCount > 1)) + { + // + // Read the next short. + // + ulTemp = *(unsigned short *)pucData; + + // + // Perform the CRC on these two bytes. + // + ulCrc = CRC32_ITER(ulCrc, ulTemp); + ulCrc = CRC32_ITER(ulCrc, ulTemp >> 8); + + // + // Skip these input bytes. + // + pucData += 2; + ulCount -= 2; + } + + // + // While there is at least a word remaining in the data buffer, perform + // four steps of the CRC to consume a word. + // + while(ulCount > 3) + { + // + // Read the next word. + // + ulTemp = *(unsigned long *)pucData; + + // + // Perform the CRC on these four bytes. + // + ulCrc = CRC32_ITER(ulCrc, ulTemp); + ulCrc = CRC32_ITER(ulCrc, ulTemp >> 8); + ulCrc = CRC32_ITER(ulCrc, ulTemp >> 16); + ulCrc = CRC32_ITER(ulCrc, ulTemp >> 24); + + // + // Skip these input bytes. + // + pucData += 4; + ulCount -= 4; + } + + // + // If there is a short left in the input buffer, then perform two steps of + // the CRC. + // + if(ulCount > 1) + { + // + // Read the short. + // + ulTemp = *(unsigned short *)pucData; + + // + // Perform the CRC on these two bytes. + // + ulCrc = CRC32_ITER(ulCrc, ulTemp); + ulCrc = CRC32_ITER(ulCrc, ulTemp >> 8); + + // + // Skip these input bytes. + // + pucData += 2; + ulCount -= 2; + } + + // + // If there is a final byte remaining in the input buffer, then perform a + // single step of the CRC. + // + if(ulCount != 0) + { + ulCrc = CRC32_ITER(ulCrc, *pucData); + } + + // + // Return the resulting CRC-16 value. + // + return(ulCrc); +} + +//***************************************************************************** +// +// Close the Doxygen group. +//! @} +// +//***************************************************************************** -- cgit v1.3.1