| /* ------------------------------------------------------------------ |
| * Copyright (C) 1998-2009 PacketVideo |
| * |
| * 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. |
| * ------------------------------------------------------------------- |
| */ |
| /**************************************************************************************** |
| Portions of this file are derived from the following 3GPP standard: |
| |
| 3GPP TS 26.073 |
| ANSI-C code for the Adaptive Multi-Rate (AMR) speech codec |
| Available from http://www.3gpp.org |
| |
| (C) 2004, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC) |
| Permission to distribute, modify and use this file under the standard license |
| terms listed above has been obtained from the copyright holder. |
| ****************************************************************************************/ |
| /* |
| Pathname: ./gsm-amr/c/src/div_s.c |
| |
| ------------------------------------------------------------------------------ |
| REVISION HISTORY |
| |
| Description: Created separate file for the div_s function. Sync'ed up |
| with the current template and fixed tabs. |
| |
| Description: Making changes based on review meeting. |
| |
| Description: Made changes based on P3 review meeting. |
| |
| Description: Changing abort() to exit(0). |
| |
| Description: Made the following changes |
| 1. Unrolled the division loop to make three comparison per |
| pass, using only five iterations of the loop and saving |
| shifts cycles |
| |
| Who: Date: |
| Description: |
| |
| ------------------------------------------------------------------------------ |
| INPUT AND OUTPUT DEFINITIONS |
| |
| Inputs: |
| var1 = 16 bit signed integer (Word16) whose value falls in |
| the range : 0x0000 <= var1 <= 0x7fff. |
| var2 = 16 bit signed integer (Word16) whose value falls in |
| the range : 0x0000 <= var1 <= 0x7fff. |
| |
| Local Stores/Buffers/Pointers Needed: |
| None |
| |
| Global Stores/Buffers/Pointers Needed: |
| None |
| |
| Outputs: |
| var_out = quotient of var1 divided by var2 (Word16) |
| |
| Pointers and Buffers Modified: |
| None |
| |
| Local Stores Modified: |
| None |
| |
| Global Stores Modified: |
| None |
| |
| ------------------------------------------------------------------------------ |
| FUNCTION DESCRIPTION |
| |
| This function produces a result which is the fractional integer division of |
| var1 by var2; var1 and var2 must be positive and var2 must be greater or equal |
| to var1; the result is positive (leading bit equal to 0) and truncated to 16 |
| bits. If var1 = var2 then div(var1,var2) = 32767. |
| |
| ------------------------------------------------------------------------------ |
| REQUIREMENTS |
| |
| None |
| |
| ------------------------------------------------------------------------------ |
| REFERENCES |
| |
| [1] basicop2.c, ETS Version 2.0.0, February 8, 1999 |
| |
| ------------------------------------------------------------------------------ |
| PSEUDO-CODE |
| |
| Word16 div_s (Word16 var1, Word16 var2) |
| { |
| Word16 var_out = 0; |
| Word16 iteration; |
| Word32 L_num; |
| Word32 L_denom; |
| Word16 abort_flag = 0; |
| |
| if ((var1 > var2) || (var1 < 0)) |
| { |
| printf ("Division Error var1=%d var2=%d\n", var1, var2); |
| abort_flag = 1; |
| exit(0); |
| } |
| if ((var1 != 0) && (abort_flag == 0)) |
| { |
| if (var1 == var2) |
| { |
| var_out = MAX_16; |
| } |
| else |
| { |
| L_num = (Word32) var1; |
| L_denom = (Word32) var2; |
| |
| for (iteration = 15; iteration > 0; iteration--) |
| { |
| var_out <<= 1; |
| L_num <<= 1; |
| |
| if (L_num >= L_denom) |
| { |
| L_num -= L_denom; |
| var_out += 1; |
| } |
| } |
| } |
| } |
| |
| #if (WMOPS) |
| multiCounter[currCounter].div_s++; |
| #endif |
| return (var_out); |
| } |
| |
| ------------------------------------------------------------------------------ |
| RESOURCES USED |
| When the code is written for a specific target processor the |
| the resources used should be documented below. |
| |
| STACK USAGE: [stack count for this module] + [variable to represent |
| stack usage for each subroutine called] |
| |
| where: [stack usage variable] = stack usage for [subroutine |
| name] (see [filename].ext) |
| |
| DATA MEMORY USED: x words |
| |
| PROGRAM MEMORY USED: x words |
| |
| CLOCK CYCLES: [cycle count equation for this module] + [variable |
| used to represent cycle count for each subroutine |
| called] |
| |
| where: [cycle count variable] = cycle count for [subroutine |
| name] (see [filename].ext) |
| |
| ------------------------------------------------------------------------------ |
| */ |
| |
| |
| /*---------------------------------------------------------------------------- |
| ; INCLUDES |
| ----------------------------------------------------------------------------*/ |
| #include "basic_op.h" |
| |
| /*---------------------------------------------------------------------------- |
| ; MACROS |
| ; Define module specific macros here |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; DEFINES |
| ; Include all pre-processor statements here. Include conditional |
| ; compile variables also. |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; LOCAL FUNCTION DEFINITIONS |
| ; Function Prototype declaration |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; LOCAL STORE/BUFFER/POINTER DEFINITIONS |
| ; Variable declaration - defined here and used outside this module |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; EXTERNAL FUNCTION REFERENCES |
| ; Declare functions defined elsewhere and referenced in this module |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES |
| ; Declare variables used in this module but defined elsewhere |
| ----------------------------------------------------------------------------*/ |
| |
| /*---------------------------------------------------------------------------- |
| ; FUNCTION CODE |
| ----------------------------------------------------------------------------*/ |
| Word16 div_s(Word16 var1, Word16 var2) |
| { |
| /*---------------------------------------------------------------------------- |
| ; Define all local variables |
| ----------------------------------------------------------------------------*/ |
| Word16 var_out = 0; |
| Word16 iteration; |
| Word32 L_num; |
| Word32 L_denom; |
| Word32 L_denom_by_2; |
| Word32 L_denom_by_4; |
| |
| /*---------------------------------------------------------------------------- |
| ; Function body here |
| ----------------------------------------------------------------------------*/ |
| if ((var1 > var2) || (var1 < 0)) |
| { |
| return 0; // used to exit(0); |
| } |
| if (var1) |
| { |
| if (var1 != var2) |
| { |
| |
| L_num = (Word32) var1; |
| L_denom = (Word32) var2; |
| L_denom_by_2 = (L_denom << 1); |
| L_denom_by_4 = (L_denom << 2); |
| for (iteration = 5; iteration > 0; iteration--) |
| { |
| var_out <<= 3; |
| L_num <<= 3; |
| |
| if (L_num >= L_denom_by_4) |
| { |
| L_num -= L_denom_by_4; |
| var_out |= 4; |
| } |
| |
| if (L_num >= L_denom_by_2) |
| { |
| L_num -= L_denom_by_2; |
| var_out |= 2; |
| } |
| |
| if (L_num >= (L_denom)) |
| { |
| L_num -= (L_denom); |
| var_out |= 1; |
| } |
| |
| } |
| } |
| else |
| { |
| var_out = MAX_16; |
| } |
| } |
| |
| #if (WMOPS) |
| multiCounter[currCounter].div_s++; |
| #endif |
| |
| /*---------------------------------------------------------------------------- |
| ; Return nothing or data or data pointer |
| ----------------------------------------------------------------------------*/ |
| return (var_out); |
| } |