diff options
Diffstat (limited to 'drivers/staging/brcm80211/util/qmath.c')
| -rw-r--r-- | drivers/staging/brcm80211/util/qmath.c | 681 |
1 files changed, 681 insertions, 0 deletions
diff --git a/drivers/staging/brcm80211/util/qmath.c b/drivers/staging/brcm80211/util/qmath.c new file mode 100644 index 0000000..40c9929 --- /dev/null +++ b/drivers/staging/brcm80211/util/qmath.c @@ -0,0 +1,681 @@ +/* + * 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 "qmath.h" + +/* +Description: This function saturate input 32 bit number into a 16 bit number. +If input number is greater than 0x7fff then output is saturated to 0x7fff. +else if input number is less than 0xffff8000 then output is saturated to 0xffff8000 +else output is same as input. +*/ +s16 qm_sat32(s32 op) +{ + s16 result; + if (op > (s32) 0x7fff) { + result = 0x7fff; + } else if (op < (s32) 0xffff8000) { + result = (s16) (0x8000); + } else { + result = (s16) op; + } + return result; +} + +/* +Description: This function multiply two input 16 bit numbers and return the 32 bit result. +This multiplication is similar to compiler multiplication. This operation is defined if +16 bit multiplication on the processor platform is cheaper than 32 bit multiplication (as +the most of qmath functions can be replaced with processor intrinsic instructions). +*/ +s32 qm_mul321616(s16 op1, s16 op2) +{ + return (s32) (op1) * (s32) (op2); +} + +/* +Description: This function make 16 bit multiplication and return the result in 16 bits. +To fit the result into 16 bits the 32 bit multiplication result is right +shifted by 16 bits. +*/ +s16 qm_mul16(s16 op1, s16 op2) +{ + s32 result; + result = ((s32) (op1) * (s32) (op2)); + return (s16) (result >> 16); +} + +/* +Description: This function multiply two 16 bit numbers and return the result in 32 bits. +This function remove the extra sign bit created by the multiplication by leftshifting the +32 bit multiplication result by 1 bit before returning the result. So the output is +twice that of compiler multiplication. (i.e. qm_muls321616(2,3)=12). +When both input 16 bit numbers are 0x8000, then the result is saturated to 0x7fffffff. +*/ +s32 qm_muls321616(s16 op1, s16 op2) +{ + s32 result; + if (op1 == (s16) (0x8000) && op2 == (s16) (0x8000)) { + result = 0x7fffffff; + } else { + result = ((s32) (op1) * (s32) (op2)); + result = result << 1; + } + return result; +} + +/* +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 32 bit subtraction and return the 32bit result. +If the result overflow 32 bits, the output will be saturated to 32bits. +*/ +s32 qm_sub32(s32 op1, s32 op2) +{ + s32 result; + result = op1 - op2; + if (op1 >= 0 && op2 < 0 && result < 0) { + result = 0x7fffffff; + } else if (op1 < 0 && op2 > 0 && result > 0) { + result = 0x80000000; + } + return result; +} + +/* +Description: This function multiply input 16 bit numbers and accumulate the result +into the input 32 bit number and return the 32 bit accumulated result. +If the accumulation result in overflow, then the output will be saturated. +*/ +s32 qm_mac321616(s32 acc, s16 op1, s16 op2) +{ + s32 result; + result = qm_add32(acc, qm_mul321616(op1, op2)); + 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 32 bit right shift when shift is +ve. +This function make a 32 bit saturated left shift when shift is -ve. This function +return the result of the shift operation. +*/ +s32 qm_shr32(s32 op, int shift) +{ + return qm_shl32(op, -shift); +} + +/* +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 16 bit number. +Example: qm_norm16(0x0080) = 7. +*/ +s16 qm_norm16(s16 op) +{ + u16 u16extraSignBits; + if (op == 0) { + return 15; + } else { + u16extraSignBits = 0; + while ((op >> 15) == (op >> 14)) { + u16extraSignBits++; + op = op << 1; + } + } + return u16extraSignBits; +} + +/* +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; +} + +/* +Description: This function divide two 16 bit unsigned numbers. +The numerator should be less than denominator. So the quotient is always less than 1. +This function return the quotient in q.15 format. +*/ +s16 qm_div_s(s16 num, s16 denom) +{ + s16 var_out; + s16 iteration; + s32 L_num; + s32 L_denom; + L_num = (num) << 15; + L_denom = (denom) << 15; + for (iteration = 0; iteration < 15; iteration++) { + L_num <<= 1; + if (L_num >= L_denom) { + L_num = qm_sub32(L_num, L_denom); + L_num = qm_add32(L_num, 1); + } + } + var_out = (s16) (L_num & 0x7fff); + return var_out; +} + +/* +Description: This function compute the absolute value of a 16 bit number. +*/ +s16 qm_abs16(s16 op) +{ + if (op < 0) { + if (op == (s16) 0xffff8000) { + return 0x7fff; + } else { + return -op; + } + } else { + return op; + } +} + +/* +Description: This function divide two 16 bit numbers. +The quotient is returned through return value. +The qformat of the quotient is returned through the pointer (qQuotient) passed +to this function. The qformat of quotient is adjusted appropriately such that +the quotient occupies all 16 bits. +*/ +s16 qm_div16(s16 num, s16 denom, s16 *qQuotient) +{ + s16 sign; + s16 nNum, nDenom; + sign = num ^ denom; + num = qm_abs16(num); + denom = qm_abs16(denom); + nNum = qm_norm16(num); + nDenom = qm_norm16(denom); + num = qm_shl16(num, nNum - 1); + denom = qm_shl16(denom, nDenom); + *qQuotient = nNum - 1 - nDenom + 15; + if (sign >= 0) { + return qm_div_s(num, denom); + } else { + return -qm_div_s(num, denom); + } +} + +/* +Description: This function compute absolute value of a 32 bit number. +*/ +s32 qm_abs32(s32 op) +{ + if (op < 0) { + if (op == (s32) 0x80000000) { + return 0x7fffffff; + } else { + return -op; + } + } else { + return op; + } +} + +/* +Description: This function divide two 32 bit numbers. The division is performed +by considering only important 16 bits in 32 bit numbers. +The quotient is returned through return value. +The qformat of the quotient is returned through the pointer (qquotient) passed +to this function. The qformat of quotient is adjusted appropriately such that +the quotient occupies all 16 bits. +*/ +s16 qm_div163232(s32 num, s32 denom, s16 *qquotient) +{ + s32 sign; + s16 nNum, nDenom; + sign = num ^ denom; + num = qm_abs32(num); + denom = qm_abs32(denom); + nNum = qm_norm32(num); + nDenom = qm_norm32(denom); + num = qm_shl32(num, nNum - 1); + denom = qm_shl32(denom, nDenom); + *qquotient = nNum - 1 - nDenom + 15; + if (sign >= 0) { + return qm_div_s((s16) (num >> 16), (s16) (denom >> 16)); + } else { + return -qm_div_s((s16) (num >> 16), (s16) (denom >> 16)); + } +} + +/* +Description: This function multiply a 32 bit number with a 16 bit number. +The multiplicaton result is right shifted by 16 bits to fit the result +into 32 bit output. +*/ +s32 qm_mul323216(s32 op1, s16 op2) +{ + s16 hi; + u16 lo; + s32 result; + hi = op1 >> 16; + lo = (s16) (op1 & 0xffff); + result = qm_mul321616(hi, op2); + result = result + (qm_mulsu321616(op2, lo) >> 16); + return result; +} + +/* +Description: This function multiply signed 16 bit number with unsigned 16 bit number and return +the result in 32 bits. +*/ +s32 qm_mulsu321616(s16 op1, u16 op2) +{ + return (s32) (op1) * op2; +} + +/* +Description: This function multiply 32 bit number with 16 bit number. The multiplication result is +right shifted by 15 bits to fit the result into 32 bits. Right shifting by only 15 bits instead of +16 bits is done to remove the extra sign bit formed by multiplication from the return value. +When the input numbers are 0x80000000, 0x8000 the return value is saturated to 0x7fffffff. +*/ +s32 qm_muls323216(s32 op1, s16 op2) +{ + s16 hi; + u16 lo; + s32 result; + hi = op1 >> 16; + lo = (s16) (op1 & 0xffff); + result = qm_muls321616(hi, op2); + result = qm_add32(result, (qm_mulsu321616(op2, lo) >> 15)); + return result; +} + +/* +Description: This function multiply two 32 bit numbers. The multiplication result is right +shifted by 32 bits to fit the multiplication result into 32 bits. The right shifted +multiplication result is returned as output. +*/ +s32 qm_mul32(s32 a, s32 b) +{ + s16 hi1, hi2; + u16 lo1, lo2; + s32 result; + hi1 = a >> 16; + hi2 = b >> 16; + lo1 = (u16) (a & 0xffff); + lo2 = (u16) (b & 0xffff); + result = qm_mul321616(hi1, hi2); + result = result + (qm_mulsu321616(hi1, lo2) >> 16); + result = result + (qm_mulsu321616(hi2, lo1) >> 16); + return result; +} + +/* +Description: This function multiply two 32 bit numbers. The multiplication result is +right shifted by 31 bits to fit the multiplication result into 32 bits. The right +shifted multiplication result is returned as output. Right shifting by only 31 bits +instead of 32 bits is done to remove the extra sign bit formed by multiplication. +When the input numbers are 0x80000000, 0x80000000 the return value is saturated to +0x7fffffff. +*/ +s32 qm_muls32(s32 a, s32 b) +{ + s16 hi1, hi2; + u16 lo1, lo2; + s32 result; + hi1 = a >> 16; + hi2 = b >> 16; + lo1 = (u16) (a & 0xffff); + lo2 = (u16) (b & 0xffff); + result = qm_muls321616(hi1, hi2); + result = qm_add32(result, (qm_mulsu321616(hi1, lo2) >> 15)); + result = qm_add32(result, (qm_mulsu321616(hi2, lo1) >> 15)); + result = qm_add32(result, (qm_mulu16(lo1, lo2) >> 15)); + return result; +} + +/* 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; + + /* Logerithm of negative values is undefined. + * assert N is greater than 0. + */ + /* ASSERT(N > 0); */ + + /* 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; +} + +/* +Description: +This routine compute 1/N. +This routine reformates the given no N as N * 2^qN where N is in between 0.5 and 1.0 +in q.15 format in 16 bits. So the problem now boils down to finding the inverse of a +q.15 no in 16 bits which is in the range of 0.5 to 1.0. The output is always between +2.0 to 1. So the output is 2.0 to 1.0 in q.30 format. Once the final output format is found +by taking the qN into account. Inverse is found with newton rapson method. Initially +inverse (x) is guessed as 1/0.75 (with appropriate sign). The new guess is calculated +using the formula x' = 2*x - N*x*x. After 4 or 5 iterations the inverse is very close to +inverse of N. +Inputs: +N - number to which 1/N has to be found. +qn - q format of N. +sqrtN - address where 1/N has to be written. +qsqrtN - address where q format of 1/N has to be written. +*/ +#define qx 29 +void qm_1byN(s32 N, s16 qN, s32 *result, s16 *qResult) +{ + s16 normN; + s32 s32firstTerm, s32secondTerm, x; + int i; + + normN = qm_norm32(N); + + /* limit N to least significant 16 bits. 15th bit is the sign bit. */ + N = qm_shl32(N, normN - 16); + qN = qN + normN - 16 - 15; + /* -15 is added to treat N as 16 bit q.15 number in the range from 0.5 to 1 */ + + /* Take the initial guess as 1/0.75 in qx format with appropriate sign. */ + if (N >= 0) { + x = (s32) ((1 / 0.75) * (1 << qx)); + /* input no is in the range 0.5 to 1. So 1/0.75 is taken as initial guess. */ + } else { + x = (s32) ((1 / -0.75) * (1 << qx)); + /* input no is in the range -0.5 to -1. So 1/-0.75 is taken as initial guess. */ + } + + /* iterate the equation x = 2*x - N*x*x for 4 times. */ + for (i = 0; i < 4; i++) { + s32firstTerm = qm_shl32(x, 1); /* s32firstTerm = 2*x in q.29 */ + s32secondTerm = + qm_muls321616((s16) (s32firstTerm >> 16), + (s16) (s32firstTerm >> 16)); + /* s32secondTerm = x*x in q.(29+1-16)*2+1 */ + s32secondTerm = + qm_muls321616((s16) (s32secondTerm >> 16), (s16) N); + /* s32secondTerm = N*x*x in q.((29+1-16)*2+1)-16+15+1 i.e. in q.29 */ + x = qm_sub32(s32firstTerm, s32secondTerm); + /* can be added directly as both are in q.29 */ + } + + /* Bring the x to q.30 format. */ + *result = qm_shl32(x, 1); + /* giving the output in q.30 format for q.15 input in 16 bits. */ + + /* compute the final q format of the result. */ + *qResult = -qN + 30; /* adjusting the q format of actual output */ + + return; +} + +#undef qx |
