| /* |
| ** 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); |
| } |
| |
