rov_int_mandelbrot_test1.c - math test module for |template <typename T> class rov_int_template|
Posted by Anonymous on Wed 18th Mar 2026 19:26
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/*
 * MIT License
 *
 * Copyright (c) 2026 Roland Mainz <roland.mainz@nrubsig.org>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

/*
 * rov_int_mandelbrot_test1.c - math test module for |template <typename T> class rov_int_template|
 *
 * WARNING: This module must be compileable with ISO C and ISO C++ compilers
 * for benchmarking and testing purposes!
 */

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

#define USE_ROV_INT_TEMPLATE002_TYPES 1

#ifdef USE_ROV_INT_TEMPLATE002_TYPES
/*
 * Compile with ISO C++ integer wrapper class
 */
#include "rov_int_template002.h"

typedef rov_int_template<int32_t> test_int32_t;
typedef rov_int_template<int64_t> test_int64_t;
#else
/*
 * Compile with ISO C99/C11 compiler
 */
#error XXX
typedef int32_t test_int32_t;
typedef int64_t test_int64_t;
#endif /* USE_ROV_INT_TEMPLATE002_TYPES */

/* Mandelbrot parameters */
#define MANDELBROT_VIEW_WIDTH           (132LL) /*72*/
#define MANDELBROT_VIEW_HEIGHT          (50LL)
#define MANDELBROT_VIEW_MAX_ITER        (100)

/* Fixed-point math (fpx) scale */
#define FPX_SCALE       (1000LL)  /* fpx scale: 1000 <--> 1.0 */

/*
 * |fpx_mul()| - fpx multiply: (a*b)/FPX_SCALE using 64-bit
 */
static inline
test_int32_t fpx_mul(test_int32_t a, test_int32_t b)
{
    return (test_int32_t)(((test_int64_t)a * (test_int64_t)b) / FPX_SCALE);
}

/*
 * Iterations && ASCII "palette"
 * - FIXME: Make this a cmdline argument
 */
static const char mandelbrot_palette[] =
    " .:-+*0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ#";
const size_t mandelbrot_palette_len = sizeof(mandelbrot_palette) - 1;

static
void do_fxmath_mandelbrot(void)
{
    /*
     * Mandelbrot view window:
     * fpx: x in [-2, 1], y range adjusted for aspect
     */
    const test_int32_t x_min   = -2000;  /* was: -2.000 * FPX_SCALE */
    const test_int32_t x_max   =  1000;  /* was: 1.000 * FPX_SCALE */
    const test_int32_t x_range = x_max - x_min;

    /* y_range = x_range * MANDELBROT_VIEW_HEIGHT / MANDELBROT_VIEW_WIDTH, centered around 0 */
    const test_int32_t y_range =
        (test_int32_t)(((test_int64_t)x_range * MANDELBROT_VIEW_HEIGHT) / MANDELBROT_VIEW_WIDTH);
    const test_int32_t y_min   = -(y_range / 2);
    const test_int32_t y_max   =  (y_range - y_range / 2);

    /* Precompute escape radius squared, scaled: (2*FPX_SCALE)^2 */
    const test_int64_t esc2 = (test_int64_t)((2LL * FPX_SCALE) * (2LL * FPX_SCALE));

    for (int j = 0; j < MANDELBROT_VIEW_HEIGHT; j++) {
        /* cy = y_min + j * (y_max - y_min) / (MANDELBROT_VIEW_HEIGHT-1) */
        test_int32_t cy = y_min;

        test_int64_t t = (test_int64_t)(y_max - y_min);
        t = (t * (test_int64_t)j) / (test_int64_t)(MANDELBROT_VIEW_HEIGHT - 1);
        cy = (test_int32_t)((test_int64_t)y_min + t);

        for (int i = 0; i < MANDELBROT_VIEW_WIDTH; i++) {
            /* cx = x_min + i * x_range / (MANDELBROT_VIEW_WIDTH-1) */
            test_int32_t cx = x_min;

            test_int64_t t = (test_int64_t)x_range;
            t = (t * (test_int64_t)i) / (test_int64_t)(MANDELBROT_VIEW_WIDTH - 1);
            cx = (test_int32_t)((test_int64_t)x_min + t);

            test_int32_t zx = 0, zy = 0;
            int iter = 0;

            /* Loop in fpx: z_{n+1} = z_n^2 + c */
            for (;;) {
                test_int64_t sumsq = (test_int64_t)zx * (test_int64_t)zx + (test_int64_t)zy * (test_int64_t)zy;
                if (sumsq > esc2)
                        break;
                if (iter >= MANDELBROT_VIEW_MAX_ITER)
                        break;

                test_int32_t zx2 = fpx_mul(zx, zx);
                test_int32_t zy2 = fpx_mul(zy, zy);
                test_int32_t xy  = fpx_mul(zx, zy);

                test_int32_t nx = (zx2 - zy2) + cx;
                test_int32_t ny = (test_int32_t)((test_int64_t)xy * 2) + cy;

                zx = nx;
                zy = ny;
                iter++;
            }

            /* Map mandelbrot iterations to palette index */
            size_t idx = (iter >= MANDELBROT_VIEW_MAX_ITER)
                ? (mandelbrot_palette_len - 1)
                : (int)(((test_int64_t)iter * (mandelbrot_palette_len - 1)) / MANDELBROT_VIEW_MAX_ITER);
            (void)putchar(mandelbrot_palette[idx]);
        }

        (void)putchar('\n');
    }
}

static
void do_unit_tests1(void)
{
        /*
         * FIXME: clang++ throws SIGFPE on Debian Bulleye, we need to add code to catch this
         */
        {
                rov_int_template<int32_t> x = 0;
                rov_int_template<int32_t> y = 0;
                (void)printf("res (x/y)=%d\n", (int)(x/y));
        }
        {
                rov_int_template<int32_t> x = 0;
                (void)printf("res (x/0)=%d\n", (int)(x/0));
        }
        {
                rov_int_template<int32_t> x = 0;
                rov_int_template<int32_t> y = 0;
                (void)printf("res (x/=y)=%d\n", (int)(x/=y));
        }
}

int main(int ac, char *av[])
{
#if 0
        do_unit_tests1();
#endif

#if 1
        do_fxmath_mandelbrot();
#endif
        return EXIT_SUCCESS;
}