mirror of https://gitee.com/openkylin/linux.git
309 lines
7.9 KiB
C
309 lines
7.9 KiB
C
/*
|
|
* 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=[0:1:31], 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
|
|
};
|
|
|
|
#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;
|
|
}
|