implemented write_grid and read_grid function

1 files changed, 155 insertions, 9 deletions

diff --git a/src/grids.c b/src/grids.c
index 10a934e..a6d35df 100644
--- a/src/grids.c
+++ b/src/grids.c
@@ -1,3 +1,4 @@
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include "grids.h"
@@ -5,23 +6,31 @@
 /*
  * Creates a grid for storing the results of the escape algorithm
  */
-grid_t* create_grid(const size_t x, const size_t y){
+grid_t* create_grid(const size_t x, const size_t y, double complex lower_left, double complex upper_right){
     if(x <= 0 || y <= 0) return NULL;
 
     const size_t size = x * y;
     size_t* data = malloc(size * sizeof(size_t));
-    if(!data) return NULL;
+    if(!data){
+        fprintf(stderr, "Error allocating %zu grid points for grid\n", size);
+        return NULL;
+    }
 
     grid_t* grid = malloc(sizeof(grid_t));
     if(!grid){
+        fprintf(stderr, "Error allocating grid\n");
         free(data);
         return NULL;
     }
 
-    grid->x = x;
-    grid->y = y;
-    grid->size = size;
-    grid->data = data;
+    *grid = (grid_t){
+        .x = x,
+        .y = y,
+        .lower_left = lower_left,
+        .upper_right = upper_right,
+        .data = data
+
+    };
 
     return grid;
 }
@@ -29,7 +38,7 @@ grid_t* create_grid(const size_t x, const size_t y){
 /*
  * Sets all entries of a grid to the value val
  */
-void set_grid(grid_t* grid, const double val){
+void set_grid(grid_t* grid, const size_t val){
     if(!grid || !grid->data) return;
     memset(grid->data, val, grid->size);
 }
@@ -40,7 +49,7 @@ void set_grid(grid_t* grid, const double val){
 grid_t* copy_grid(const grid_t* grid){
     if(!grid || !grid->data) return NULL;
 
-    grid_t* grid_copy = create_grid(grid->x, grid->y);
+    grid_t* grid_copy = create_grid(grid->x, grid->y, grid->lower_left, grid->upper_right);
     if(!grid_copy) return NULL;
 
     memcpy(grid_copy->data, grid->data, grid->size);
@@ -65,6 +74,7 @@ void free_grid(grid_t* grid){
  */
 bool grid_equal(const grid_t* grid1, const grid_t* grid2){
     return grid1->x == grid2->x && grid1->y == grid2->y &&
+        grid1->lower_left == grid2->lower_left && grid1->upper_right == grid2->upper_right &&
         memcmp(grid1->data, grid2->data, grid1->size) == 0;
 }
 
@@ -72,10 +82,146 @@ bool grid_equal(const grid_t* grid1, const grid_t* grid2){
  * Checks if two grids have a given maximum difference
  */
 bool grid_allclose(const grid_t *grid1, const grid_t *grid2, const size_t max_error){
-    if(grid1->x != grid2->x || grid1->y != grid2->y) return false;
+    if(grid1->x != grid2->x || grid1->y != grid2->y ||
+            grid1->lower_left != grid2->lower_left || grid1->upper_right != grid2->upper_right){
+        return false;
+    }
     const size_t size = grid1->size;
     for(size_t i = 0; i < size; i++){
+        //FIXME: figure out how to handle difference between two unsigned values
+        //       possibly cast them to sized longs?
         if(abs(grid1->data[i] - grid2->data[i]) >= max_error) return false;
     }
     return true;
 }
+
+
+/*
+ * Converts a grid point into the corresponding complex number
+ */
+double complex grid_to_complex(const grid_t* grid, const size_t index) {
+    const size_t x_res = grid->x;
+    const size_t y_res = grid->y;
+    const double x_min = creal(grid->lower_left);
+    const double x_max = creal(grid->upper_right);
+    const double y_min = cimag(grid->lower_left);
+    const double y_max = cimag(grid->upper_right);
+
+    const double x_step = (x_max - x_min) / (double)x_res;
+    const double y_step = (y_max - y_min) / (double)y_res;
+
+    const size_t x_index = index % x_res;
+    const size_t y_index = index / y_res;
+
+    const double x = x_min + x_index * x_step;
+    const double y = y_min + y_index * y_step;
+
+    return x + y * I;
+}
+
+/*
+ * Writes a grid to a file in the .grid format
+ *
+ * Returns 0 on success
+ *
+ * The .grid format is a binary file format
+ * The first 3 bytes of the file are a magic number defined in grids.h
+ * The next 16 bytes are the grid dimensions (x then y)
+ * Following are 32 bytes are the bounding of the complex region (lower_left then upper_right)
+ * The rest of the file is the data for the grid, which should be exactly x*y*8 bytes
+ */
+int write_grid(FILE* restrict file, const grid_t *grid){
+    if(grid->size == 0 || !grid->data ){
+        return GRID_NO_DATA;
+    }
+
+    unsigned char magic_num[3];
+    for(size_t i = 0; i < 3; i++){
+        magic_num[i] = (GRID_MAGIC_NUMBER >> (2*i)) & 0xFF;
+    }
+
+    if(fwrite(magic_num, 1, 3, file) != 3) return GRID_WRITE_ERROR;
+
+    if(fwrite(&grid->x, sizeof(size_t), 1, file) != 1 ||
+       fwrite(&grid->y, sizeof(size_t), 1, file) != 1 ||
+       fwrite(&grid->lower_left, sizeof(double complex), 1, file) != 1 ||
+       fwrite(&grid->upper_right, sizeof(double complex), 1, file) != 1){
+        return GRID_WRITE_ERROR;
+    }
+
+    if(fwrite(grid->data, sizeof(size_t), grid->size, file) != grid->size){
+        return GRID_WRITE_ERROR;
+    }
+
+    return 0;
+}
+
+/*
+ * Creates a grid from a .grid file, reading the amount of data as specified by the file
+ * For more details on the .grid format see write_grid
+ *
+ * Ignores remainder of file if it has finished reading but is not at the end ofthe file
+ */
+grid_t* read_grid(FILE* restrict file){
+    // Make sure the file has a magic goose (GRID_MAGIC_NUMBER)
+    unsigned char magic_num[3];
+    size_t read_count = fread(magic_num, 1, 3, file);
+
+    if(read_count != 3){
+        perror("Error reading file\n");
+        return NULL;
+    }
+    for(size_t i = 0; i < 3; i++){
+        unsigned char magic_byte = (GRID_MAGIC_NUMBER >> (2*i)) & 0xFF;
+        if(magic_byte != magic_num[i]){
+            fprintf(stderr, "Error reading file, can't find magic %d\n", GRID_MAGIC_NUMBER);
+            return NULL;
+        }
+    }
+
+    size_t x = 0;
+    size_t y = 0;
+    read_count = fread(&x, sizeof(size_t), 1, file);
+    if(read_count != 1){
+        perror("Error reading file\n");
+        return NULL;
+    }
+    read_count = fread(&y, sizeof(size_t), 1, file);
+    if(read_count != 1){
+        perror("Error reading file\n");
+        return NULL;
+    }
+
+    double complex lower_left = 0;
+    double complex upper_right = 0; 
+    read_count = fread(&lower_left, sizeof(double complex), 1, file);
+    if(read_count != 1){
+        perror("Error reading file\n");
+        return NULL;
+    }
+    read_count = fread(&upper_right, sizeof(double complex), 1, file);
+    if(read_count != 1){
+        perror("Error reading file\n");
+        return NULL;
+    }
+
+    //TODO: look into mmaping the file to data, offseting by the bounding and resolution information
+    //      this would likely require an alloc_grid function, similar to jeff's implementation in hw03
+    grid_t* grid = create_grid(x, y, lower_left, upper_right);
+    if(!grid){
+        return NULL;
+    }
+
+    read_count = fread(grid->data, sizeof(size_t), grid->size, file);
+    if(read_count != grid->size){
+        fprintf(stderr, "Error reading file, expected %zu grid points but only found %zu\n", grid->size, read_count);
+        free_grid(grid);
+        return NULL;
+    }
+
+    if(!feof(file)){
+        fprintf(stderr, "Finished reading %zu grid points but not at the end of the file\n", read_count);
+    }
+
+    return grid;
+}