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Added: Working non standard threaded SIMD implementation untested.

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This commit is contained in:
Yashar Alan Zenker
2026-07-04 19:26:25 +02:00
parent b630fa965e
commit f28aff6e72
3 changed files with 162 additions and 30 deletions
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Implementierung/main.c
+1 -1
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@@ -223,7 +223,7 @@ int main(int argc, char** argv)
tricorn_V3(complexA,width,height,resolution,n,colored,tempArr);
break;
case 4:
// Uses non SIMD threaded version
// Uses SIMD threaded version
tricorn_V4(complexA,width,height,resolution,n,colored,tempArr);
break;
default:
Implementierung/tricorn_V4.c
+152 -28
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@@ -1,8 +1,22 @@
#include "tricorn_V2.h"
#include "tricorn_V4.h"
static void compute(void * args);
static unsigned converge(float c_real, float c_imag, unsigned n);
static size_t get_thread_count();
typedef struct {
unsigned n;
_Bool color;
_Bool flipped;
float start_r;
float start_i;
float res;
size_t start_row;
size_t stop_row;
size_t width;
unsigned char* img;
} compute_args;
/**
* @brief Generates a Tricorn fractal image using an optimized SISD implementation.
* @param start The starting complex coordinate (bottom-left or top-left depending on height sign).
@@ -14,51 +28,152 @@ static unsigned converge(float c_real, float c_imag, unsigned n);
* @param img Pointer to the pre-allocated memory buffer where the bitmap data will be stored.
*/
void tricorn_V4(float complex start, size_t width, ssize_t height, float res, unsigned n, _Bool color, unsigned char* img){
int bytesPerColor = color ? 3 : 1;
const ssize_t min_pixels_per_thread = 50;
_Bool flipped = height < 0;
height = flipped ? -height : height;
size_t thread_count = get_thread_count();
if(height >= min_pixels_per_thread)
while((height/thread_count) < min_pixels_per_thread) thread_count--;
else thread_count = 1;
printf("%lu \n",thread_count);
const size_t y_step = (height+thread_count-1)/thread_count;
const float start_r = crealf(start);
const float start_i = cimagf(start);
float directional_res = (flipped ? -1.0f: 1.0f)*res;
pthread_t threads[thread_count];
for(size_t i = 0; i < thread_count; i++){
compute_args* args = malloc(sizeof(*args));
args->start_r =start_r;
args->start_i =start_i-i*directional_res*y_step;
args->start_row = i*y_step;
args->stop_row = height < (args->start_row+y_step) ? height: (args->start_row+y_step);
args->width = width;
args-> flipped = flipped;
args->color = color;
args->res = res;
args->img = img;
args->n = n;
if(pthread_create(&threads[i],NULL,compute,args)){
compute(args);
free(args);
args = NULL;
}
}
for(int i = 0; i < thread_count; i++){
pthread_join(threads[i],NULL);
}
return;
}
static void compute(void * vargs){
compute_args *args = vargs;
vargs = NULL;
int bytes_per_color = args->color ? 3 : 1;
// Absolute height for iteration purposes
ssize_t actual_height = height < 0 ? (ssize_t)(-height) : height;
ssize_t imag_step = height < 0 ? -1:1;
size_t simd_width = (args->width / 4) * 4;
float c_start_real = creal(start);
float c_start_imag = cimag(start);
float c_start_real = args->start_r;
__m128 four = _mm_set1_ps(4.0f);
__m128 minus_two = _mm_set1_ps(-2.0f);
float c_imag = c_start_imag;
float vertical_step = imag_step * res;
size_t position = 0;
float c_imag = args->start_i;
__m128 c_imag_vector = _mm_set1_ps(c_imag);
float four_res = 4 * args->res;
float vertical_step = (args->flipped? -1.0f: 1.0f) * args->res;
__m128 vertical_step_vector = _mm_set1_ps(vertical_step);
// Simple iteration over every pixel in the picture
for(ssize_t y = 0; y < actual_height; y++){
for(size_t y = args->start_row; y < args->stop_row;y++) {
size_t x = 0;
__m128 c_real_vector = _mm_setr_ps(c_start_real,c_start_real + 1.0f*args->res,c_start_real + 2.0f*args->res, c_start_real + 3.0f*args->res);
for(; x < simd_width;x += 4) { //SIMD Loop
__m128 real = _mm_setzero_ps();
__m128 imag = _mm_setzero_ps();
__m128i iterations = _mm_setzero_si128();
__m128i active_mask = _mm_set1_epi32(-1);
// Calculate imaginary part on each row as it stays the same
for(unsigned i = 0; i < args->n;i++) {
__m128 real2 = _mm_mul_ps(real,real);
__m128 imag2 = _mm_mul_ps(imag,imag);
float c_real = c_start_real;
for(size_t x = 0; x < width; x++){
unsigned value = converge(c_real,c_imag,n);
__m128 unbounded = _mm_cmple_ps(_mm_add_ps(real2,imag2),four);
__m128i unbounded_i = _mm_castps_si128(unbounded);
// Pixel value position in the output array
active_mask = _mm_and_si128(active_mask,unbounded_i);
if(!color){ // Grayscale colors as specified by the assignment r = g = b
img[position] = value;
}
else{ // Temporary colors with random multipliers
img[position] = ((value*3) % 255);
img[position + 1] = ((value*2) % 255) ;
img[position + 2] = ((value*5) % 255);
if(_mm_test_all_zeros(active_mask,active_mask)) {
break;
}
iterations = _mm_sub_epi32(iterations,active_mask);
imag = _mm_add_ps(c_imag_vector,_mm_mul_ps(minus_two, _mm_mul_ps(real,imag)));
real = _mm_add_ps(_mm_sub_ps(real2,imag2),c_real_vector);
}
position += bytesPerColor;
c_real += res;
__m128i mod64 = _mm_and_si128(iterations, _mm_set1_epi32(63));
__m128i times4 = _mm_slli_epi32(mod64, 2);
__m128i values = _mm_sub_epi32(_mm_set1_epi32(255), times4);
__m128i max_iter = _mm_set1_epi32(args->n);
__m128i is_max = _mm_cmpeq_epi32(iterations, max_iter);
values = _mm_andnot_si128(is_max, values);
unsigned int value_array[4];
_mm_storeu_si128((__m128i*)value_array,values);
for(unsigned i = 0 ; i < 4;i++) {
unsigned int value = value_array[i];
size_t position = (y*args->width + (x+i)) * bytes_per_color;
if(!args->color) {
args->img[position] = value;
}
else {
args->img[position] = ((value*3) % 255);
args->img[position + 1] = ((value*2) % 255);
args->img[position + 2] = ((value*5) % 255);
}
}
c_real_vector = _mm_add_ps(c_real_vector,_mm_set1_ps(four_res));
}
for(;x < args->width; x++) {
float c_real = c_start_real + (x*args->res);
unsigned int value = converge(c_real,c_imag,args->n);
size_t position = (y*args->width + x) * bytes_per_color;
if(!args->color) {
args->img[position] = value;
}
else {
args->img[position] = ((value*3) % 255);
args->img[position + 1] = ((value*2) % 255);
args->img[position + 2] = ((value*5) % 255);
}
}
c_imag -= vertical_step;
c_imag_vector = _mm_sub_ps(c_imag_vector,vertical_step_vector);
}
free(args);
args = NULL;
}
// Iterative application of the equation given by the assignment
static inline unsigned converge(float c_real, float c_imag, unsigned n) {
const float convergenceLimit = 4.0f;
static unsigned converge(float c_real, float c_imag, unsigned n) {
float real = 0.0f;
float imag = 0.0f;
@@ -66,7 +181,7 @@ static inline unsigned converge(float c_real, float c_imag, unsigned n) {
float real2 = real * real;
float imag2 = imag * imag;
if (real2 + imag2 > convergenceLimit) {
if (real2 + imag2 > 4.0f) {
return 255 - 4 * (i % 64);
}
@@ -75,3 +190,12 @@ static inline unsigned converge(float c_real, float c_imag, unsigned n) {
}
return 0;
}
static inline size_t get_thread_count(){
#ifdef WIN32
SYSTEM_INFO sysinfo;
GetSystemInfo(&sysinfo);
return sysinfo.dwNumberOfProcessors;
#else
return sysconf(_SC_NPROCESSORS_ONLN);
#endif
}
Implementierung/tricorn_V4.h
+8
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@@ -2,4 +2,12 @@
#include <stddef.h>
#include <math.h>
#include <sys/types.h>
#include <immintrin.h>
#include <pthread.h>
#ifdef WIN32
#include <sysinfoapi.h>
#else
#include <unistd.h>
#endif
void tricorn_V4(float complex start, size_t width, ssize_t height, float res, unsigned n, _Bool color, unsigned char* img);