/* | |
** Copyright 2003-2010, VisualOn, Inc. | |
** | |
** Licensed under the Apache License, Version 2.0 (the "License"); | |
** you may not use this file except in compliance with the License. | |
** You may obtain a copy of the License at | |
** | |
** http://www.apache.org/licenses/LICENSE-2.0 | |
** | |
** Unless required by applicable law or agreed to in writing, software | |
** distributed under the License is distributed on an "AS IS" BASIS, | |
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
** See the License for the specific language governing permissions and | |
** limitations under the License. | |
*/ | |
/***************************************************************************** | |
* This file contains operations in double precision. * | |
* These operations are not standard double precision operations. * | |
* They are used where single precision is not enough but the full 32 bits * | |
* precision is not necessary. For example, the function Div_32() has a * | |
* 24 bits precision which is enough for our purposes. * | |
* * | |
* The double precision numbers use a special representation: * | |
* * | |
* L_32 = hi<<16 + lo<<1 * | |
* * | |
* L_32 is a 32 bit integer. * | |
* hi and lo are 16 bit signed integers. * | |
* As the low part also contains the sign, this allows fast multiplication. * | |
* * | |
* 0x8000 0000 <= L_32 <= 0x7fff fffe. * | |
* * | |
* We will use DPF (Double Precision Format )in this file to specify * | |
* this special format. * | |
***************************************************************************** | |
*/ | |
#include "typedef.h" | |
#include "basic_op.h" | |
#include "oper_32b.h" | |
/***************************************************************************** | |
* * | |
* Function L_Extract() * | |
* * | |
* Extract from a 32 bit integer two 16 bit DPF. * | |
* * | |
* Arguments: * | |
* * | |
* L_32 : 32 bit integer. * | |
* 0x8000 0000 <= L_32 <= 0x7fff ffff. * | |
* hi : b16 to b31 of L_32 * | |
* lo : (L_32 - hi<<16)>>1 * | |
***************************************************************************** | |
*/ | |
__inline void VO_L_Extract (Word32 L_32, Word16 *hi, Word16 *lo) | |
{ | |
*hi = (Word16)(L_32 >> 16); | |
*lo = (Word16)((L_32 & 0xffff) >> 1); | |
return; | |
} | |
/***************************************************************************** | |
* * | |
* Function L_Comp() * | |
* * | |
* Compose from two 16 bit DPF a 32 bit integer. * | |
* * | |
* L_32 = hi<<16 + lo<<1 * | |
* * | |
* Arguments: * | |
* * | |
* hi msb * | |
* lo lsf (with sign) * | |
* * | |
* Return Value : * | |
* * | |
* 32 bit long signed integer (Word32) whose value falls in the * | |
* range : 0x8000 0000 <= L_32 <= 0x7fff fff0. * | |
* * | |
***************************************************************************** | |
*/ | |
Word32 L_Comp (Word16 hi, Word16 lo) | |
{ | |
Word32 L_32; | |
L_32 = L_deposit_h (hi); | |
return (L_mac (L_32, lo, 1)); /* = hi<<16 + lo<<1 */ | |
} | |
/***************************************************************************** | |
* Function Mpy_32() * | |
* * | |
* Multiply two 32 bit integers (DPF). The result is divided by 2**31 * | |
* * | |
* L_32 = (hi1*hi2)<<1 + ( (hi1*lo2)>>15 + (lo1*hi2)>>15 )<<1 * | |
* * | |
* This operation can also be viewed as the multiplication of two Q31 * | |
* number and the result is also in Q31. * | |
* * | |
* Arguments: * | |
* * | |
* hi1 hi part of first number * | |
* lo1 lo part of first number * | |
* hi2 hi part of second number * | |
* lo2 lo part of second number * | |
* * | |
***************************************************************************** | |
*/ | |
__inline Word32 Mpy_32 (Word16 hi1, Word16 lo1, Word16 hi2, Word16 lo2) | |
{ | |
Word32 L_32; | |
L_32 = (hi1 * hi2); | |
L_32 += (hi1 * lo2) >> 15; | |
L_32 += (lo1 * hi2) >> 15; | |
L_32 <<= 1; | |
return (L_32); | |
} | |
/***************************************************************************** | |
* Function Mpy_32_16() * | |
* * | |
* Multiply a 16 bit integer by a 32 bit (DPF). The result is divided * | |
* by 2**15 * | |
* * | |
* * | |
* L_32 = (hi1*lo2)<<1 + ((lo1*lo2)>>15)<<1 * | |
* * | |
* Arguments: * | |
* * | |
* hi hi part of 32 bit number. * | |
* lo lo part of 32 bit number. * | |
* n 16 bit number. * | |
* * | |
***************************************************************************** | |
*/ | |
__inline Word32 Mpy_32_16 (Word16 hi, Word16 lo, Word16 n) | |
{ | |
Word32 L_32; | |
L_32 = (hi * n)<<1; | |
L_32 += (((lo * n)>>15)<<1); | |
return (L_32); | |
} | |
/***************************************************************************** | |
* * | |
* Function Name : Div_32 * | |
* * | |
* Purpose : * | |
* Fractional integer division of two 32 bit numbers. * | |
* L_num / L_denom. * | |
* L_num and L_denom must be positive and L_num < L_denom. * | |
* L_denom = denom_hi<<16 + denom_lo<<1 * | |
* denom_hi is a normalize number. * | |
* * | |
* Inputs : * | |
* * | |
* L_num * | |
* 32 bit long signed integer (Word32) whose value falls in the * | |
* range : 0x0000 0000 < L_num < L_denom * | |
* * | |
* L_denom = denom_hi<<16 + denom_lo<<1 (DPF) * | |
* * | |
* denom_hi * | |
* 16 bit positive normalized integer whose value falls in the * | |
* range : 0x4000 < hi < 0x7fff * | |
* denom_lo * | |
* 16 bit positive integer whose value falls in the * | |
* range : 0 < lo < 0x7fff * | |
* * | |
* Return Value : * | |
* * | |
* L_div * | |
* 32 bit long signed integer (Word32) whose value falls in the * | |
* range : 0x0000 0000 <= L_div <= 0x7fff ffff. * | |
* * | |
* Algorithm: * | |
* * | |
* - find = 1/L_denom. * | |
* First approximation: approx = 1 / denom_hi * | |
* 1/L_denom = approx * (2.0 - L_denom * approx ) * | |
* * | |
* - result = L_num * (1/L_denom) * | |
***************************************************************************** | |
*/ | |
Word32 Div_32 (Word32 L_num, Word16 denom_hi, Word16 denom_lo) | |
{ | |
Word16 approx, hi, lo, n_hi, n_lo; | |
Word32 L_32; | |
/* First approximation: 1 / L_denom = 1/denom_hi */ | |
approx = div_s ((Word16) 0x3fff, denom_hi); | |
/* 1/L_denom = approx * (2.0 - L_denom * approx) */ | |
L_32 = Mpy_32_16 (denom_hi, denom_lo, approx); | |
L_32 = L_sub ((Word32) 0x7fffffffL, L_32); | |
hi = L_32 >> 16; | |
lo = (L_32 & 0xffff) >> 1; | |
L_32 = Mpy_32_16 (hi, lo, approx); | |
/* L_num * (1/L_denom) */ | |
hi = L_32 >> 16; | |
lo = (L_32 & 0xffff) >> 1; | |
VO_L_Extract (L_num, &n_hi, &n_lo); | |
L_32 = Mpy_32 (n_hi, n_lo, hi, lo); | |
L_32 = L_shl2(L_32, 2); | |
return (L_32); | |
} | |