/*
   * Checksum functions for Hexagon
   *
   * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 and
   * only version 2 as published by the Free Software Foundation.
   *
   * This program 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.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   * 02110-1301, USA.
   */
  
  /*  This was derived from arch/alpha/lib/checksum.c  */
  
  
  #include <linux/module.h>
  #include <linux/string.h>
  
  #include <asm/byteorder.h>
  #include <net/checksum.h>
  #include <linux/uaccess.h>
  #include <asm/intrinsics.h>
  
  
  /*  Vector value operations  */
  #define SIGN(x, y)	((0x8000ULL*x)<<y)
  #define CARRY(x, y)	((0x0002ULL*x)<<y)
  #define SELECT(x, y)	((0x0001ULL*x)<<y)
  
  #define VR_NEGATE(a, b, c, d)	(SIGN(a, 48) + SIGN(b, 32) + SIGN(c, 16) \
  	+ SIGN(d, 0))
  #define VR_CARRY(a, b, c, d)	(CARRY(a, 48) + CARRY(b, 32) + CARRY(c, 16) \
  	+ CARRY(d, 0))
  #define VR_SELECT(a, b, c, d)	(SELECT(a, 48) + SELECT(b, 32) + SELECT(c, 16) \
  	+ SELECT(d, 0))
  
  
  /* optimized HEXAGON V3 intrinsic version */
  static inline unsigned short from64to16(u64 x)
  {
  	u64 sum;
  
  	sum = HEXAGON_P_vrmpyh_PP(x^VR_NEGATE(1, 1, 1, 1),
  			     VR_SELECT(1, 1, 1, 1));
  	sum += VR_CARRY(0, 0, 1, 0);
  	sum = HEXAGON_P_vrmpyh_PP(sum, VR_SELECT(0, 0, 1, 1));
  
  	return 0xFFFF & sum;
  }
  
  /*
   * computes the checksum of the TCP/UDP pseudo-header
   * returns a 16-bit checksum, already complemented.
   */
  __sum16 csum_tcpudp_magic(unsigned long saddr, unsigned long daddr,
  			  unsigned short len, unsigned short proto,
  			  __wsum sum)
  {
  	return (__force __sum16)~from64to16(
  		(__force u64)saddr + (__force u64)daddr +
  		(__force u64)sum + ((len + proto) << 8));
  }
  
  __wsum csum_tcpudp_nofold(unsigned long saddr, unsigned long daddr,
  			  unsigned short len, unsigned short proto,
  			  __wsum sum)
  {
  	u64 result;
  
  	result = (__force u64)saddr + (__force u64)daddr +
  		 (__force u64)sum + ((len + proto) << 8);
  
  	/* Fold down to 32-bits so we don't lose in the typedef-less
  	   network stack.  */
  	/* 64 to 33 */
  	result = (result & 0xffffffffUL) + (result >> 32);
  	/* 33 to 32 */
  	result = (result & 0xffffffffUL) + (result >> 32);
  	return (__force __wsum)result;
  }
  EXPORT_SYMBOL(csum_tcpudp_nofold);
  
  /*
   * Do a 64-bit checksum on an arbitrary memory area..
   *
   * This isn't a great routine, but it's not _horrible_ either. The
   * inner loop could be unrolled a bit further, and there are better
   * ways to do the carry, but this is reasonable.
   */
  
  /* optimized HEXAGON intrinsic version, with over read fixed */
  unsigned int do_csum(const void *voidptr, int len)
  {
  	u64 sum0, sum1, x0, x1, *ptr8_o, *ptr8_e, *ptr8;
  	int i, start, mid, end, mask;
  	const char *ptr = voidptr;
  	unsigned short *ptr2;
  	unsigned int *ptr4;
  
  	if (len <= 0)
  		return 0;
  
  	start = 0xF & (16-(((int) ptr) & 0xF)) ;
  	mask  = 0x7fffffffUL >> HEXAGON_R_cl0_R(len);
  	start = start & mask ;
  
  	mid = len - start;
  	end = mid & 0xF;
  	mid = mid>>4;
  	sum0 = mid << 18;
  	sum1 = 0;
  
  	if (start & 1)
  		sum0 += (u64) (ptr[0] << 8);
  	ptr2 = (unsigned short *) &ptr[start & 1];
  	if (start & 2)
  		sum1 += (u64) ptr2[0];
  	ptr4 = (unsigned int *) &ptr[start & 3];
  	if (start & 4) {
  		sum0 = HEXAGON_P_vrmpyhacc_PP(sum0,
  			VR_NEGATE(0, 0, 1, 1)^((u64)ptr4[0]),
  			VR_SELECT(0, 0, 1, 1));
  		sum0 += VR_SELECT(0, 0, 1, 0);
  	}
  	ptr8 = (u64 *) &ptr[start & 7];
  	if (start & 8) {
  		sum1 = HEXAGON_P_vrmpyhacc_PP(sum1,
  			VR_NEGATE(1, 1, 1, 1)^(ptr8[0]),
  			VR_SELECT(1, 1, 1, 1));
  		sum1 += VR_CARRY(0, 0, 1, 0);
  	}
  	ptr8_o = (u64 *) (ptr + start);
  	ptr8_e = (u64 *) (ptr + start + 8);
  
  	if (mid) {
  		x0 = *ptr8_e; ptr8_e += 2;
  		x1 = *ptr8_o; ptr8_o += 2;
  		if (mid > 1)
  			for (i = 0; i < mid-1; i++) {
  				sum0 = HEXAGON_P_vrmpyhacc_PP(sum0,
  					x0^VR_NEGATE(1, 1, 1, 1),
  					VR_SELECT(1, 1, 1, 1));
  				sum1 = HEXAGON_P_vrmpyhacc_PP(sum1,
  					x1^VR_NEGATE(1, 1, 1, 1),
  					VR_SELECT(1, 1, 1, 1));
  				x0 = *ptr8_e; ptr8_e += 2;
  				x1 = *ptr8_o; ptr8_o += 2;
  			}
  		sum0 = HEXAGON_P_vrmpyhacc_PP(sum0, x0^VR_NEGATE(1, 1, 1, 1),
  			VR_SELECT(1, 1, 1, 1));
  		sum1 = HEXAGON_P_vrmpyhacc_PP(sum1, x1^VR_NEGATE(1, 1, 1, 1),
  			VR_SELECT(1, 1, 1, 1));
  	}
  
  	ptr4 = (unsigned int *) &ptr[start + (mid * 16) + (end & 8)];
  	if (end & 4) {
  		sum1 = HEXAGON_P_vrmpyhacc_PP(sum1,
  			VR_NEGATE(0, 0, 1, 1)^((u64)ptr4[0]),
  			VR_SELECT(0, 0, 1, 1));
  		sum1 += VR_SELECT(0, 0, 1, 0);
  	}
  	ptr2 = (unsigned short *) &ptr[start + (mid * 16) + (end & 12)];
  	if (end & 2)
  		sum0 += (u64) ptr2[0];
  
  	if (end & 1)
  		sum1 += (u64) ptr[start + (mid * 16) + (end & 14)];
  
  	ptr8 = (u64 *) &ptr[start + (mid * 16)];
  	if (end & 8) {
  		sum0 = HEXAGON_P_vrmpyhacc_PP(sum0,
  			VR_NEGATE(1, 1, 1, 1)^(ptr8[0]),
  			VR_SELECT(1, 1, 1, 1));
  		sum0 += VR_CARRY(0, 0, 1, 0);
  	}
  	sum0 = HEXAGON_P_vrmpyh_PP((sum0+sum1)^VR_NEGATE(0, 0, 0, 1),
  		VR_SELECT(0, 0, 1, 1));
  	sum0 += VR_NEGATE(0, 0, 0, 1);
  	sum0 = HEXAGON_P_vrmpyh_PP(sum0, VR_SELECT(0, 0, 1, 1));
  
  	if (start & 1)
  		sum0 = (sum0 << 8) | (0xFF & (sum0 >> 8));
  
  	return 0xFFFF & sum0;
  }
  
  /*
   * copy from ds while checksumming, otherwise like csum_partial
   */
  __wsum
  csum_partial_copy_nocheck(const void *src, void *dst, int len, __wsum sum)
  {
  	memcpy(dst, src, len);
  	return csum_partial(dst, len, sum);
  }