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software Cordic implementation.
This commit is contained in:
Jean-François DEL NERO
parent
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188
src/common/cordic/cordic16.h
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188
src/common/cordic/cordic16.h
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///////////////////////////////////////////////////////////////////////////////////
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//-------------------------------------------------------------------------------//
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//-------------------------------------------------------------------------------//
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//-----------H----H--X----X-----CCCCC----22222----0000-----0000------11----------//
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//----------H----H----X-X-----C--------------2---0----0---0----0--1--1-----------//
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//---------HHHHHH-----X------C----------22222---0----0---0----0-----1------------//
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//--------H----H----X--X----C----------2-------0----0---0----0-----1-------------//
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//-------H----H---X-----X---CCCCC-----222222----0000-----0000----1111------------//
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//-------------------------------------------------------------------------------//
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//----------------------------------------------------- http://hxc2001.free.fr --//
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///////////////////////////////////////////////////////////////////////////////////
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// File : cordic16.h
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// Contains: 16 bits cordic
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//
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// This file is part of rf-tools.
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//
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// Written by: Jean-François DEL NERO
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//
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// Copyright (C) 2022-2026 Jean-François DEL NERO
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//
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// You are free to do what you want with this code.
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// A credit is always appreciated if you use it into your product :)
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//
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// Change History (most recent first):
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///////////////////////////////////////////////////////////////////////////////////
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//#define CORDIC16_DEBUG 1
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typedef int16_t cordic16_wordsize;
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#define CORDIC16_BITS_CNT 16
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// 1 / K
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#define CORDIC16_K1 0.6072529350088812561694
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#define CORDIC16_PI 3.1415926536897932384626
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#define CORDIC16_MUL ((float)(1 << (CORDIC16_BITS_CNT-2))) // -2 -> one bit for the sign, one bit to have a symetric min max value
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#define CORDIC16_1K ((cordic16_wordsize)(CORDIC16_MUL*CORDIC16_K1))
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#define CORDIC16_HALF_PI_INT (((cordic16_wordsize)(CORDIC16_MUL*(CORDIC16_PI/2))))
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#define CORDIC16_PI_INT ((int)(CORDIC16_MUL*CORDIC16_PI))
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#define CORDIC_0_2PI 1
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#ifdef CORDIC_0_2PI
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#define CORDIC16_MIN_ANGLE 0
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#define CORDIC16_MAX_ANGLE ((int)(2*CORDIC16_MUL*CORDIC16_PI))
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#else
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#define CORDIC16_MIN_ANGLE ((int)(-CORDIC16_MUL*CORDIC16_PI))
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#define CORDIC16_MAX_ANGLE ((int)(CORDIC16_MUL*CORDIC16_PI))
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#endif
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#define CORDIC16_FAST_CODE 1
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///////////////////////////////////////////////////////////////////////////////////
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/*
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table generator :
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printf("\n");
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for(i=0;i<64;i++)
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{
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printf("(cordic16_wordsize)(%.20f*CORDIC16_MUL),", atan(pow(2, -i)) );
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}
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printf("\n");
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*/
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static cordic16_wordsize cordic_atanpowtab [] =
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{
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(cordic16_wordsize)(0.78539816339744827900*CORDIC16_MUL),(cordic16_wordsize)(0.46364760900080609352*CORDIC16_MUL),(cordic16_wordsize)(0.24497866312686414347*CORDIC16_MUL),(cordic16_wordsize)(0.12435499454676143816*CORDIC16_MUL),
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(cordic16_wordsize)(0.06241880999595735002*CORDIC16_MUL),(cordic16_wordsize)(0.03123983343026827744*CORDIC16_MUL),(cordic16_wordsize)(0.01562372862047683129*CORDIC16_MUL),(cordic16_wordsize)(0.00781234106010111114*CORDIC16_MUL),
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(cordic16_wordsize)(0.00390623013196697176*CORDIC16_MUL),(cordic16_wordsize)(0.00195312251647881876*CORDIC16_MUL),(cordic16_wordsize)(0.00097656218955931946*CORDIC16_MUL),(cordic16_wordsize)(0.00048828121119489829*CORDIC16_MUL),
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(cordic16_wordsize)(0.00024414062014936177*CORDIC16_MUL),(cordic16_wordsize)(0.00012207031189367021*CORDIC16_MUL),(cordic16_wordsize)(0.00006103515617420877*CORDIC16_MUL),(cordic16_wordsize)(0.00003051757811552610*CORDIC16_MUL),
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(cordic16_wordsize)(0.00001525878906131576*CORDIC16_MUL),(cordic16_wordsize)(0.00000762939453110197*CORDIC16_MUL),(cordic16_wordsize)(0.00000381469726560650*CORDIC16_MUL),(cordic16_wordsize)(0.00000190734863281019*CORDIC16_MUL),
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(cordic16_wordsize)(0.00000095367431640596*CORDIC16_MUL),(cordic16_wordsize)(0.00000047683715820309*CORDIC16_MUL),(cordic16_wordsize)(0.00000023841857910156*CORDIC16_MUL),(cordic16_wordsize)(0.00000011920928955078*CORDIC16_MUL),
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(cordic16_wordsize)(0.00000005960464477539*CORDIC16_MUL),(cordic16_wordsize)(0.00000002980232238770*CORDIC16_MUL),(cordic16_wordsize)(0.00000001490116119385*CORDIC16_MUL),(cordic16_wordsize)(0.00000000745058059692*CORDIC16_MUL),
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(cordic16_wordsize)(0.00000000372529029846*CORDIC16_MUL),(cordic16_wordsize)(0.00000000186264514923*CORDIC16_MUL),(cordic16_wordsize)(0.00000000093132257462*CORDIC16_MUL),(cordic16_wordsize)(0.00000000046566128731*CORDIC16_MUL),
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(cordic16_wordsize)(0.00000000023283064365*CORDIC16_MUL),(cordic16_wordsize)(0.00000000011641532183*CORDIC16_MUL),(cordic16_wordsize)(0.00000000005820766091*CORDIC16_MUL),(cordic16_wordsize)(0.00000000002910383046*CORDIC16_MUL),
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(cordic16_wordsize)(0.00000000001455191523*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000727595761*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000363797881*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000181898940*CORDIC16_MUL),
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(cordic16_wordsize)(0.00000000000090949470*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000045474735*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000022737368*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000011368684*CORDIC16_MUL),
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(cordic16_wordsize)(0.00000000000005684342*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000002842171*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000001421085*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000000710543*CORDIC16_MUL),
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(cordic16_wordsize)(0.00000000000000355271*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000000177636*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000000088818*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000000044409*CORDIC16_MUL),
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(cordic16_wordsize)(0.00000000000000022204*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000000011102*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000000005551*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000000002776*CORDIC16_MUL),
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(cordic16_wordsize)(0.00000000000000001388*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000000000694*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000000000347*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000000000173*CORDIC16_MUL),
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(cordic16_wordsize)(0.00000000000000000087*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000000000043*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000000000022*CORDIC16_MUL),(cordic16_wordsize)(0.00000000000000000011*CORDIC16_MUL)
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};
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///////////////////////////////////////////////////////////////////////////////////
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static void cordic16(int theta, cordic16_wordsize *s, cordic16_wordsize *c)
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{
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int k;
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cordic16_wordsize tx, ty;
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cordic16_wordsize *ptr;
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cordic16_wordsize x = CORDIC16_1K;
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cordic16_wordsize y = 0;
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#ifdef CORDIC16_FAST_CODE
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cordic16_wordsize sign;
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#endif
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cordic16_wordsize sign_out;
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int z;
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ptr = (cordic16_wordsize*)&cordic_atanpowtab;
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#ifdef CORDIC_0_2PI
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theta -= CORDIC16_PI_INT;
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#endif
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z = theta;
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sign_out = 0;
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if( theta > CORDIC16_HALF_PI_INT )
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{ // > PI / 2 ?
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z = theta - CORDIC16_PI_INT; // angle -= PI
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sign_out = -1;
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}
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if( theta < -CORDIC16_HALF_PI_INT )
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{ // < -PI / 2 ?
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z = theta + CORDIC16_PI_INT; // angle += PI
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sign_out = -1;
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}
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// z <<= 2;
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for (k=0; k<CORDIC16_BITS_CNT; k++)
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{
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#ifdef CORDIC16_FAST_CODE
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// Shift the sign bit. result -1 (all bits to 1) or 0
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sign = z>>(CORDIC16_BITS_CNT-1);
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// if sign == -1, the y/x>>k sign is changed
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tx = x - (((y>>k) ^ sign) - sign);
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ty = y + (((x>>k) ^ sign) - sign);
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z -= (((*ptr++) ^ sign) - sign);
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#else
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if(z < 0)
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{ // Clockwise
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tx = x + (y>>k);
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ty = y - (x>>k);
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z += (*ptr++);
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}
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else
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{ // Counter Clockwise
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tx = x - (y>>k);
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ty = y + (x>>k);
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z -= (*ptr++);
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}
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#endif
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x = tx;
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y = ty;
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}
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*c = (x ^ sign_out) - sign_out;
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*s = (y ^ sign_out) - sign_out;
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}
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///////////////////////////////////////////////////////////////////////////////////
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#ifdef CORDIC16_DEBUG
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static void print_cordic_stat()
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{
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int i;
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printf("CORDIC Stats :\n");
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printf("CORDIC BITS : %d (0x%X)\n",CORDIC16_BITS_CNT,CORDIC16_BITS_CNT);
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printf("CORDIC MUL : %f (0x%X)\n",CORDIC16_MUL,(int)CORDIC16_MUL);
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printf("CORDIC MIN ANGLE : %d (0x%X)\n",CORDIC16_MIN_ANGLE,CORDIC16_MIN_ANGLE);
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printf("CORDIC MAX ANGLE : %d (0x%X)\n",CORDIC16_MAX_ANGLE,CORDIC16_MAX_ANGLE);
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printf("CORDIC HALF PI INT : %d (0x%X)\n",CORDIC16_HALF_PI_INT,CORDIC16_HALF_PI_INT);
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printf("CORDIC PI INT : %d (0x%X)\n",CORDIC16_PI_INT,CORDIC16_PI_INT);
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printf("ATAN Table :\n");
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for(i=0;i<CORDIC16_BITS_CNT;i++)
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{
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printf("0x%.4X,",cordic_atanpowtab[i]);
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}
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printf("\n");
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printf("\n");
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}
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#endif
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