diff options
Diffstat (limited to 'drivers/staging/brcm80211/brcmsmac/phy/wlc_phy_qmath.c')
| -rw-r--r-- | drivers/staging/brcm80211/brcmsmac/phy/wlc_phy_qmath.c | 296 |
1 files changed, 296 insertions, 0 deletions
diff --git a/drivers/staging/brcm80211/brcmsmac/phy/wlc_phy_qmath.c b/drivers/staging/brcm80211/brcmsmac/phy/wlc_phy_qmath.c new file mode 100644 index 000000000000..c98176fd0aae --- /dev/null +++ b/drivers/staging/brcm80211/brcmsmac/phy/wlc_phy_qmath.c @@ -0,0 +1,296 @@ +/* + * 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 <linux/types.h> + +#include "wlc_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. */ + s16errorApproximation = (s16) qm_mulu16(u16offset, (u16) (log_table[s16tableIndex + 1] - log_table[s16tableIndex])); /* q.15 */ + + s32log = qm_add16((s16) s32log, s16errorApproximation); /* q.15 format */ + + /* 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 */ + s32log = qm_shl32(s32log, s16norm - 16); /* q.15+s16norm-16 format */ + + /* 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; +} |