drivers/net/wireless/broadcom/brcm80211/brcmsmac/phy/phy_qmath.c - linux-mtk - Git at Google

 /*
  * Copyright (c) 2010 Broadcom Corporation
  *
  * Permission to use, copy, modify, and/or distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
  * copyright notice and this permission notice appear in all copies.
  *
  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
  * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */

 #include "phy_qmath.h"

 /*
  * Description: This function make 16 bit unsigned multiplication.
  * To fit the output into 16 bits the 32 bit multiplication result is right
  * shifted by 16 bits.
  */
 u16 qm_mulu16(u16 op1, u16 op2)
 {
 	return (u16) (((u32) op1 * (u32) op2) >> 16);
 }

 /*
  * Description: This function make 16 bit multiplication and return the result
  * in 16 bits. To fit the multiplication result into 16 bits the multiplication
  * result is right shifted by 15 bits. Right shifting 15 bits instead of 16 bits
  * is done to remove the extra sign bit formed due to the multiplication.
  * When both the 16bit inputs are 0x8000 then the output is saturated to
  * 0x7fffffff.
  */
 s16 qm_muls16(s16 op1, s16 op2)
 {
 	s32 result;
 	if (op1 == (s16) 0x8000 && op2 == (s16) 0x8000)
 		result = 0x7fffffff;
 	else
 		result = ((s32) (op1) * (s32) (op2));

 	return (s16) (result >> 15);
 }

 /*
  * Description: This function add two 32 bit numbers and return the 32bit
  * result. If the result overflow 32 bits, the output will be saturated to
  * 32bits.
  */
 s32 qm_add32(s32 op1, s32 op2)
 {
 	s32 result;
 	result = op1 + op2;
 	if (op1 < 0 && op2 < 0 && result > 0)
 		result = 0x80000000;
 	else if (op1 > 0 && op2 > 0 && result < 0)
 		result = 0x7fffffff;

 	return result;
 }

 /*
  * Description: This function add two 16 bit numbers and return the 16bit
  * result. If the result overflow 16 bits, the output will be saturated to
  * 16bits.
  */
 s16 qm_add16(s16 op1, s16 op2)
 {
 	s16 result;
 	s32 temp = (s32) op1 + (s32) op2;
 	if (temp > (s32) 0x7fff)
 		result = (s16) 0x7fff;
 	else if (temp < (s32) 0xffff8000)
 		result = (s16) 0xffff8000;
 	else
 		result = (s16) temp;

 	return result;
 }

 /*
  * Description: This function make 16 bit subtraction and return the 16bit
  * result. If the result overflow 16 bits, the output will be saturated to
  * 16bits.
  */
 s16 qm_sub16(s16 op1, s16 op2)
 {
 	s16 result;
 	s32 temp = (s32) op1 - (s32) op2;
 	if (temp > (s32) 0x7fff)
 		result = (s16) 0x7fff;
 	else if (temp < (s32) 0xffff8000)
 		result = (s16) 0xffff8000;
 	else
 		result = (s16) temp;

 	return result;
 }

 /*
  * Description: This function make a 32 bit saturated left shift when the
  * specified shift is +ve. This function will make a 32 bit right shift when
  * the specified shift is -ve. This function return the result after shifting
  * operation.
  */
 s32 qm_shl32(s32 op, int shift)
 {
 	int i;
 	s32 result;
 	result = op;
 	if (shift > 31)
 		shift = 31;
 	else if (shift < -31)
 		shift = -31;
 	if (shift >= 0) {
 		for (i = 0; i < shift; i++)
 			result = qm_add32(result, result);
 	} else {
 		result = result >> (-shift);
 	}

 	return result;
 }

 /*
  * Description: This function make a 16 bit saturated left shift when the
  * specified shift is +ve. This function will make a 16 bit right shift when
  * the specified shift is -ve. This function return the result after shifting
  * operation.
  */
 s16 qm_shl16(s16 op, int shift)
 {
 	int i;
 	s16 result;
 	result = op;
 	if (shift > 15)
 		shift = 15;
 	else if (shift < -15)
 		shift = -15;
 	if (shift > 0) {
 		for (i = 0; i < shift; i++)
 			result = qm_add16(result, result);
 	} else {
 		result = result >> (-shift);
 	}

 	return result;
 }

 /*
  * Description: This function make a 16 bit right shift when shift is +ve.
  * This function make a 16 bit saturated left shift when shift is -ve. This
  * function return the result of the shift operation.
  */
 s16 qm_shr16(s16 op, int shift)
 {
 	return qm_shl16(op, -shift);
 }

 /*
  * Description: This function return the number of redundant sign bits in a
  * 32 bit number. Example: qm_norm32(0x00000080) = 23
  */
 s16 qm_norm32(s32 op)
 {
 	u16 u16extraSignBits;
 	if (op == 0) {
 		return 31;
 	} else {
 		u16extraSignBits = 0;
 		while ((op >> 31) == (op >> 30)) {
 			u16extraSignBits++;
 			op = op << 1;
 		}
 	}
 	return u16extraSignBits;
 }

 /* This table is log2(1+(i/32)) where i=[0:1:32], in q.15 format */
 static const s16 log_table[] = {
 	0,
 	1455,
 	2866,
 	4236,
 	5568,
 	6863,
 	8124,
 	9352,
 	10549,
 	11716,
 	12855,
 	13968,
 	15055,
 	16117,
 	17156,
 	18173,
 	19168,
 	20143,
 	21098,
 	22034,
 	22952,
 	23852,
 	24736,
 	25604,
 	26455,
 	27292,
 	28114,
 	28922,
 	29717,
 	30498,
 	31267,
 	32024,
 	32767
 };

 #define LOG_TABLE_SIZE 32       /* log_table size */
 #define LOG2_LOG_TABLE_SIZE 5   /* log2(log_table size) */
 #define Q_LOG_TABLE 15          /* qformat of log_table */
 #define LOG10_2         19728   /* log10(2) in q.16 */

 /*
  * Description:
  * This routine takes the input number N and its q format qN and compute
  * the log10(N). This routine first normalizes the input no N.	Then N is in
  * mag*(2^x) format. mag is any number in the range 2^30-(2^31 - 1).
  * Then log2(mag * 2^x) = log2(mag) + x is computed. From that
  * log10(mag * 2^x) = log2(mag * 2^x) * log10(2) is computed.
  * This routine looks the log2 value in the table considering
  * LOG2_LOG_TABLE_SIZE+1 MSBs. As the MSB is always 1, only next
  * LOG2_OF_LOG_TABLE_SIZE MSBs are used for table lookup. Next 16 MSBs are used
  * for interpolation.
  * Inputs:
  * N - number to which log10 has to be found.
  * qN - q format of N
  * log10N - address where log10(N) will be written.
  * qLog10N - address where log10N qformat will be written.
  * Note/Problem:
  * For accurate results input should be in normalized or near normalized form.
  */
 void qm_log10(s32 N, s16 qN, s16 *log10N, s16 *qLog10N)
 {
 	s16 s16norm, s16tableIndex, s16errorApproximation;
 	u16 u16offset;
 	s32 s32log;

 	/* normalize the N. */
 	s16norm = qm_norm32(N);
 	N = N << s16norm;

 	/* The qformat of N after normalization.
 	 * -30 is added to treat the no as between 1.0 to 2.0
 	 * i.e. after adding the -30 to the qformat the decimal point will be
 	 * just rigtht of the MSB. (i.e. after sign bit and 1st MSB). i.e.
 	 * at the right side of 30th bit.
 	 */
 	qN = qN + s16norm - 30;

 	/* take the table index as the LOG2_OF_LOG_TABLE_SIZE bits right of the
 	 * MSB */
 	s16tableIndex = (s16) (N >> (32 - (2 + LOG2_LOG_TABLE_SIZE)));

 	/* remove the MSB. the MSB is always 1 after normalization. */
 	s16tableIndex =
 		s16tableIndex & (s16) ((1 << LOG2_LOG_TABLE_SIZE) - 1);

 	/* remove the (1+LOG2_OF_LOG_TABLE_SIZE) MSBs in the N. */
 	N = N & ((1 << (32 - (2 + LOG2_LOG_TABLE_SIZE))) - 1);

 	/* take the offset as the 16 MSBS after table index.
 	 */
 	u16offset = (u16) (N >> (32 - (2 + LOG2_LOG_TABLE_SIZE + 16)));

 	/* look the log value in the table. */
 	s32log = log_table[s16tableIndex];      /* q.15 format */

 	/* interpolate using the offset. q.15 format. */
 	s16errorApproximation = (s16) qm_mulu16(u16offset,
 				(u16) (log_table[s16tableIndex + 1] -
 				       log_table[s16tableIndex]));

 	 /* q.15 format */
 	s32log = qm_add16((s16) s32log, s16errorApproximation);

 	/* adjust for the qformat of the N as
 	 * log2(mag * 2^x) = log2(mag) + x
 	 */
 	s32log = qm_add32(s32log, ((s32) -qN) << 15);   /* q.15 format */

 	/* normalize the result. */
 	s16norm = qm_norm32(s32log);

 	/* bring all the important bits into lower 16 bits */
 	/* q.15+s16norm-16 format */
 	s32log = qm_shl32(s32log, s16norm - 16);

 	/* compute the log10(N) by multiplying log2(N) with log10(2).
 	 * as log10(mag * 2^x) = log2(mag * 2^x) * log10(2)
 	 * log10N in q.15+s16norm-16+1 (LOG10_2 is in q.16)
 	 */
 	*log10N = qm_muls16((s16) s32log, (s16) LOG10_2);

 	/* write the q format of the result. */
 	*qLog10N = 15 + s16norm - 16 + 1;

 	return;
 }
	/*
	* Copyright (c) 2010 Broadcom Corporation
	*
	* Permission to use, copy, modify, and/or distribute this software for any
	* purpose with or without fee is hereby granted, provided that the above
	* copyright notice and this permission notice appear in all copies.
	*
	* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
	* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
	* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
	* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
	*/

	#include "phy_qmath.h"

	/*
	* Description: This function make 16 bit unsigned multiplication.
	* To fit the output into 16 bits the 32 bit multiplication result is right
	* shifted by 16 bits.
	*/
	u16 qm_mulu16(u16 op1, u16 op2)
	{
	return (u16) (((u32) op1 * (u32) op2) >> 16);
	}

	/*
	* Description: This function make 16 bit multiplication and return the result
	* in 16 bits. To fit the multiplication result into 16 bits the multiplication
	* result is right shifted by 15 bits. Right shifting 15 bits instead of 16 bits
	* is done to remove the extra sign bit formed due to the multiplication.
	* When both the 16bit inputs are 0x8000 then the output is saturated to
	* 0x7fffffff.
	*/
	s16 qm_muls16(s16 op1, s16 op2)
	{
	s32 result;
	if (op1 == (s16) 0x8000 && op2 == (s16) 0x8000)
	result = 0x7fffffff;
	else
	result = ((s32) (op1) * (s32) (op2));

	return (s16) (result >> 15);
	}

	/*
	* Description: This function add two 32 bit numbers and return the 32bit
	* result. If the result overflow 32 bits, the output will be saturated to
	* 32bits.
	*/
	s32 qm_add32(s32 op1, s32 op2)
	{
	s32 result;
	result = op1 + op2;
	if (op1 < 0 && op2 < 0 && result > 0)
	result = 0x80000000;
	else if (op1 > 0 && op2 > 0 && result < 0)
	result = 0x7fffffff;

	return result;
	}

	/*
	* Description: This function add two 16 bit numbers and return the 16bit
	* result. If the result overflow 16 bits, the output will be saturated to
	* 16bits.
	*/
	s16 qm_add16(s16 op1, s16 op2)
	{
	s16 result;
	s32 temp = (s32) op1 + (s32) op2;
	if (temp > (s32) 0x7fff)
	result = (s16) 0x7fff;
	else if (temp < (s32) 0xffff8000)
	result = (s16) 0xffff8000;
	else
	result = (s16) temp;

	return result;
	}

	/*
	* Description: This function make 16 bit subtraction and return the 16bit
	* result. If the result overflow 16 bits, the output will be saturated to
	* 16bits.
	*/
	s16 qm_sub16(s16 op1, s16 op2)
	{
	s16 result;
	s32 temp = (s32) op1 - (s32) op2;
	if (temp > (s32) 0x7fff)
	result = (s16) 0x7fff;
	else if (temp < (s32) 0xffff8000)
	result = (s16) 0xffff8000;
	else
	result = (s16) temp;

	return result;
	}

	/*
	* Description: This function make a 32 bit saturated left shift when the
	* specified shift is +ve. This function will make a 32 bit right shift when
	* the specified shift is -ve. This function return the result after shifting
	* operation.
	*/
	s32 qm_shl32(s32 op, int shift)
	{
	int i;
	s32 result;
	result = op;
	if (shift > 31)
	shift = 31;
	else if (shift < -31)
	shift = -31;
	if (shift >= 0) {
	for (i = 0; i < shift; i++)
	result = qm_add32(result, result);
	} else {
	result = result >> (-shift);
	}

	return result;
	}

	/*
	* Description: This function make a 16 bit saturated left shift when the
	* specified shift is +ve. This function will make a 16 bit right shift when
	* the specified shift is -ve. This function return the result after shifting
	* operation.
	*/
	s16 qm_shl16(s16 op, int shift)
	{
	int i;
	s16 result;
	result = op;
	if (shift > 15)
	shift = 15;
	else if (shift < -15)
	shift = -15;
	if (shift > 0) {
	for (i = 0; i < shift; i++)
	result = qm_add16(result, result);
	} else {
	result = result >> (-shift);
	}

	return result;
	}

	/*
	* Description: This function make a 16 bit right shift when shift is +ve.
	* This function make a 16 bit saturated left shift when shift is -ve. This
	* function return the result of the shift operation.
	*/
	s16 qm_shr16(s16 op, int shift)
	{
	return qm_shl16(op, -shift);
	}

	/*
	* Description: This function return the number of redundant sign bits in a
	* 32 bit number. Example: qm_norm32(0x00000080) = 23
	*/
	s16 qm_norm32(s32 op)
	{
	u16 u16extraSignBits;
	if (op == 0) {
	return 31;
	} else {
	u16extraSignBits = 0;
	while ((op >> 31) == (op >> 30)) {
	u16extraSignBits++;
	op = op << 1;
	}
	}
	return u16extraSignBits;
	}

	/* This table is log2(1+(i/32)) where i=[0:1:32], in q.15 format */
	static const s16 log_table[] = {
	0,
	1455,
	2866,
	4236,
	5568,
	6863,
	8124,
	9352,
	10549,
	11716,
	12855,
	13968,
	15055,
	16117,
	17156,
	18173,
	19168,
	20143,
	21098,
	22034,
	22952,
	23852,
	24736,
	25604,
	26455,
	27292,
	28114,
	28922,
	29717,
	30498,
	31267,
	32024,
	32767
	};

	#define LOG_TABLE_SIZE 32 /* log_table size */
	#define LOG2_LOG_TABLE_SIZE 5 /* log2(log_table size) */
	#define Q_LOG_TABLE 15 /* qformat of log_table */
	#define LOG10_2 19728 /* log10(2) in q.16 */

	/*
	* Description:
	* This routine takes the input number N and its q format qN and compute
	* the log10(N). This routine first normalizes the input no N. Then N is in
	* mag*(2^x) format. mag is any number in the range 2^30-(2^31 - 1).
	* Then log2(mag * 2^x) = log2(mag) + x is computed. From that
	* log10(mag * 2^x) = log2(mag * 2^x) * log10(2) is computed.
	* This routine looks the log2 value in the table considering
	* LOG2_LOG_TABLE_SIZE+1 MSBs. As the MSB is always 1, only next
	* LOG2_OF_LOG_TABLE_SIZE MSBs are used for table lookup. Next 16 MSBs are used
	* for interpolation.
	* Inputs:
	* N - number to which log10 has to be found.
	* qN - q format of N
	* log10N - address where log10(N) will be written.
	* qLog10N - address where log10N qformat will be written.
	* Note/Problem:
	* For accurate results input should be in normalized or near normalized form.
	*/
	void qm_log10(s32 N, s16 qN, s16 log10N, s16 qLog10N)
	{
	s16 s16norm, s16tableIndex, s16errorApproximation;
	u16 u16offset;
	s32 s32log;

	/* normalize the N. */
	s16norm = qm_norm32(N);
	N = N << s16norm;

	/* The qformat of N after normalization.
	* -30 is added to treat the no as between 1.0 to 2.0
	* i.e. after adding the -30 to the qformat the decimal point will be
	* just rigtht of the MSB. (i.e. after sign bit and 1st MSB). i.e.
	* at the right side of 30th bit.
	*/
	qN = qN + s16norm - 30;

	/* take the table index as the LOG2_OF_LOG_TABLE_SIZE bits right of the
	* MSB */
	s16tableIndex = (s16) (N >> (32 - (2 + LOG2_LOG_TABLE_SIZE)));

	/* remove the MSB. the MSB is always 1 after normalization. */
	s16tableIndex =
	s16tableIndex & (s16) ((1 << LOG2_LOG_TABLE_SIZE) - 1);

	/* remove the (1+LOG2_OF_LOG_TABLE_SIZE) MSBs in the N. */
	N = N & ((1 << (32 - (2 + LOG2_LOG_TABLE_SIZE))) - 1);

	/* take the offset as the 16 MSBS after table index.
	*/
	u16offset = (u16) (N >> (32 - (2 + LOG2_LOG_TABLE_SIZE + 16)));

	/* look the log value in the table. */
	s32log = log_table[s16tableIndex]; /* q.15 format */

	/* interpolate using the offset. q.15 format. */
	s16errorApproximation = (s16) qm_mulu16(u16offset,
	(u16) (log_table[s16tableIndex + 1] -
	log_table[s16tableIndex]));

	/* q.15 format */
	s32log = qm_add16((s16) s32log, s16errorApproximation);

	/* adjust for the qformat of the N as
	* log2(mag * 2^x) = log2(mag) + x
	*/
	s32log = qm_add32(s32log, ((s32) -qN) << 15); /* q.15 format */

	/* normalize the result. */
	s16norm = qm_norm32(s32log);

	/* bring all the important bits into lower 16 bits */
	/* q.15+s16norm-16 format */
	s32log = qm_shl32(s32log, s16norm - 16);

	/* compute the log10(N) by multiplying log2(N) with log10(2).
	* as log10(mag * 2^x) = log2(mag * 2^x) * log10(2)
	* log10N in q.15+s16norm-16+1 (LOG10_2 is in q.16)
	*/
	*log10N = qm_muls16((s16) s32log, (s16) LOG10_2);

	/* write the q format of the result. */
	*qLog10N = 15 + s16norm - 16 + 1;

	return;
	}