PerformanceAwareProgramming/part2/haversine.c

#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <Windows.h>
#include "haversine_stdlib.h"
#include "haversine_stdlib.c"
#include <math.h>
#include "listing_0065_haversine_formula.cpp"

typedef struct Str8FindResult {
    bool     found;
    HAV_Str8 match;
    HAV_Str8 match_to_end_of_buffer;
} Str8FindResult;

static Str8FindResult FindFirstCharThatLooksLikeANumber(HAV_Str8 buffer)
{
    Str8FindResult result = {0};
    for (size_t index = 0; !result.found && index < buffer.size; index++) {
        if (HAV_CharIsDigit(buffer.data[index]) || buffer.data[index] == '+' || buffer.data[index] == '-') {
            result.found                  = true;
            result.match                  = (HAV_Str8){.data = buffer.data + index, .size = 1};
            result.match_to_end_of_buffer = (HAV_Str8){.data = result.match.data,   .size = buffer.size - index};
            break;
        }
    }
    return result;
}

static f64 StringToF64(HAV_Str8 value)
{
    f64 result = 0.f;
    Str8FindResult find_result = FindFirstCharThatLooksLikeANumber(value);
    if (!find_result.found)
        return result;

    bool negative = false;
    HAV_Str8 real_number_string = find_result.match_to_end_of_buffer;
    if (find_result.match.data[0] == '+' || find_result.match.data[0] == '-') {
        negative = find_result.match.data[0] == '-';
        real_number_string.data++;
        real_number_string.size--;
    }

    HAV_Str8BinarySplitResult number_split = HAV_Str8_BinarySplit(real_number_string, HAV_STR8("."));
    HAV_Str8 integer_part                  = number_split.lhs;
    HAV_Str8 decimal_part                  = number_split.rhs;

    uint64_t integer_part_as_u64 = 0;
    for (size_t index = 0; index < integer_part.size; index++) {
        integer_part_as_u64 *= 10;
        integer_part_as_u64 += integer_part.data[index] - '0';
    }

    uint64_t decimal_part_as_u64 = 0;
    uint64_t decimal_magnitude   = 1;
    for (size_t index = 0; index < decimal_part.size; index++) {
        decimal_part_as_u64 *= 10;
        decimal_part_as_u64 += decimal_part.data[index] - '0';
        decimal_magnitude   *= 10;
    }

    typedef union FU64 {
        f64      f64_value;
        uint64_t u64_value;
    } FU64;

    FU64 fu64      = {0};
    fu64.f64_value = HAV_CAST(f64)integer_part_as_u64 + (HAV_CAST(f64)decimal_part_as_u64 / decimal_magnitude);
    if (negative) {
        fu64.u64_value |= (1ULL << 63);
    }
    return fu64.f64_value;
}

#define PRINT_USAGE HAV_PrintLnFmt("Usage: %s [haversine_input.json] [answers.f64]", argv[0])
int main(int argc, char **argv)
{
    // NOTE: Arg Parsing
    // =========================================================================
    if (argc != 2 && argc != 3) {
        PRINT_USAGE;
        return -1;
    }

    HAV_Str8 arg_json    = {argv[1], strlen(argv[1])};
    HAV_Str8 arg_answers = {0};
    if (argc == 3)
        arg_answers = (HAV_Str8){.data = argv[2], .size = strlen(argv[2])};

    HAV_Buffer json_buffer = HAV_FileRead(arg_json.data);
    if (!HAV_BufferIsValid(json_buffer))
        return 0;

    f64 haversine_sum = 0;
    size_t pair_count = 0;
    HAV_Str8 json_it  = (HAV_Str8){.data = json_buffer.data, .size = json_buffer.size};
    for (;; pair_count++) {
        HAV_Str8BinarySplitResult x0_key = HAV_Str8_BinarySplit(json_it, HAV_STR8("x0"));
        if (!x0_key.rhs.size)
            break;

        Str8FindResult            x0_find_value = FindFirstCharThatLooksLikeANumber(x0_key.rhs);
        HAV_Str8BinarySplitResult x0_value      = HAV_Str8_BinarySplit(x0_find_value.match_to_end_of_buffer, HAV_STR8(","));

        HAV_Str8BinarySplitResult y0_key        = HAV_Str8_BinarySplit(x0_value.rhs, HAV_STR8("y0"));
        Str8FindResult            y0_find_value = FindFirstCharThatLooksLikeANumber(y0_key.rhs);
        HAV_Str8BinarySplitResult y0_value      = HAV_Str8_BinarySplit(y0_find_value.match_to_end_of_buffer, HAV_STR8(","));

        HAV_Str8BinarySplitResult x1_key        = HAV_Str8_BinarySplit(y0_value.rhs, HAV_STR8("x1"));
        Str8FindResult            x1_find_value = FindFirstCharThatLooksLikeANumber(x1_key.rhs);
        HAV_Str8BinarySplitResult x1_value      = HAV_Str8_BinarySplit(x1_find_value.match_to_end_of_buffer, HAV_STR8(","));

        HAV_Str8BinarySplitResult y1_key        = HAV_Str8_BinarySplit(x1_value.rhs, HAV_STR8("y1"));
        Str8FindResult            y1_find_value = FindFirstCharThatLooksLikeANumber(y1_key.rhs);
        HAV_Str8BinarySplitResult y1_value      = HAV_Str8_BinarySplit(y1_find_value.match_to_end_of_buffer, HAV_STR8("}"));

        f64 x0 = StringToF64(x0_value.lhs);
        f64 y0 = StringToF64(y0_value.lhs);
        f64 x1 = StringToF64(x1_value.lhs);
        f64 y1 = StringToF64(y1_value.lhs);

        #if 0
        HAV_PrintLnFmt("{x0: %.*s (%f), y0: %.*s (%f), x1 %.*s (%f), y1: %.*s (%f)}",
                       HAV_STR8_FMT(x0_value.lhs), x0,
                       HAV_STR8_FMT(y0_value.lhs), y0,
                       HAV_STR8_FMT(x1_value.lhs), x1,
                       HAV_STR8_FMT(y1_value.lhs), y1);
        #endif

        json_it = y1_value.rhs;

        f64 haversine_dist = ReferenceHaversine(x0, y0, x1, y1, /*EarthRadius*/ 6372.8);
        haversine_sum     += haversine_dist;
    }

    haversine_sum /= pair_count;
    size_t input_size = json_buffer.size;
    HAV_PrintLnFmt("Input size: %zu", input_size);
    HAV_PrintLnFmt("Pair count: %zu", pair_count);
    HAV_PrintLnFmt("Haversine sum: %f", haversine_sum);

    if (arg_answers.size) {
        HAV_Buffer answers_buffer = HAV_FileRead(arg_answers.data);
        if (HAV_BufferIsValid(answers_buffer)) {
            HAV_ASSERT(answers_buffer.size == (pair_count * sizeof(f64)) + /*Reference Sum*/ sizeof(f64));

            f64 reference_haversine_sum = 0;
            memcpy(&reference_haversine_sum, answers_buffer.data + (pair_count * sizeof(f64)), sizeof(reference_haversine_sum));

            f64 difference = reference_haversine_sum - haversine_sum;
            HAV_PrintLn(HAV_STR8("\nValidation: "));
            HAV_PrintLnFmt("Reference sum: %f", reference_haversine_sum);
            HAV_PrintLnFmt("Difference: %f", difference);
        }

    }
    return 0;
}