PerformanceAwareProgramming/part2/listing_0067_simple_haversine.cpp

166 lines
4.9 KiB
C++
Raw Normal View History

2023-06-25 12:30:56 +00:00
/* ========================================================================
(C) Copyright 2023 by Molly Rocket, Inc., All Rights Reserved.
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Please see https://computerenhance.com for more information
======================================================================== */
/* ========================================================================
LISTING 67
======================================================================== */
/* NOTE(casey): _CRT_SECURE_NO_WARNINGS is here because otherwise we cannot
call fopen(). If we replace fopen() with fopen_s() to avoid the warning,
then the code doesn't compile on Linux anymore, since fopen_s() does not
exist there.
What exactly the CRT maintainers were thinking when they made this choice,
I have no idea. */
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <math.h>
#include <sys/stat.h>
typedef uint8_t u8;
typedef uint32_t u32;
typedef uint64_t u64;
typedef int32_t b32;
typedef float f32;
typedef double f64;
struct haversine_pair
{
f64 X0, Y0;
f64 X1, Y1;
};
#include "listing_0065_haversine_formula.cpp"
#include "listing_0068_buffer.cpp"
#include "listing_0069_lookup_json_parser.cpp"
static buffer ReadEntireFile(char *FileName)
{
buffer Result = {};
FILE *File = fopen(FileName, "rb");
if(File)
{
#if _WIN32
struct __stat64 Stat;
_stat64(FileName, &Stat);
#else
struct stat Stat;
stat(FileName, &Stat);
#endif
Result = AllocateBuffer(Stat.st_size);
if(Result.Data)
{
if(fread(Result.Data, Result.Count, 1, File) != 1)
{
fprintf(stderr, "ERROR: Unable to read \"%s\".\n", FileName);
FreeBuffer(&Result);
}
}
}
else
{
fprintf(stderr, "ERROR: Unable to open \"%s\".\n", FileName);
}
return Result;
}
static f64 SumHaversineDistances(u64 PairCount, haversine_pair *Pairs)
{
f64 Sum = 0;
f64 SumCoef = 1 / (f64)PairCount;
for(u64 PairIndex = 0; PairIndex < PairCount; ++PairIndex)
{
haversine_pair Pair = Pairs[PairIndex];
f64 EarthRadius = 6372.8;
f64 Dist = ReferenceHaversine(Pair.X0, Pair.Y0, Pair.X1, Pair.Y1, EarthRadius);
Sum += SumCoef*Dist;
}
return Sum;
}
int main(int ArgCount, char **Args)
{
int Result = 1;
if((ArgCount == 2) || (ArgCount == 3))
{
buffer InputJSON = ReadEntireFile(Args[1]);
u32 MinimumJSONPairEncoding = 6*4;
u64 MaxPairCount = InputJSON.Count / MinimumJSONPairEncoding;
if(MaxPairCount)
{
buffer ParsedValues = AllocateBuffer(MaxPairCount * sizeof(haversine_pair));
if(ParsedValues.Count)
{
haversine_pair *Pairs = (haversine_pair *)ParsedValues.Data;
u64 PairCount = ParseHaversinePairs(InputJSON, MaxPairCount, Pairs);
f64 Sum = SumHaversineDistances(PairCount, Pairs);
fprintf(stdout, "Input size: %llu\n", InputJSON.Count);
fprintf(stdout, "Pair count: %llu\n", PairCount);
fprintf(stdout, "Haversine sum: %.16f\n", Sum);
if(ArgCount == 3)
{
buffer AnswersF64 = ReadEntireFile(Args[2]);
if(AnswersF64.Count >= sizeof(f64))
{
f64 *AnswerValues = (f64 *)AnswersF64.Data;
fprintf(stdout, "\nValidation:\n");
u64 RefAnswerCount = (AnswersF64.Count - sizeof(f64)) / sizeof(f64);
if(PairCount != RefAnswerCount)
{
fprintf(stdout, "FAILED - pair count doesn't match %llu.\n", RefAnswerCount);
}
f64 RefSum = AnswerValues[RefAnswerCount];
fprintf(stdout, "Reference sum: %.16f\n", RefSum);
fprintf(stdout, "Difference: %.16f\n", Sum - RefSum);
fprintf(stdout, "\n");
}
}
}
FreeBuffer(&ParsedValues);
}
else
{
fprintf(stderr, "ERROR: Malformed input JSON\n");
}
FreeBuffer(&InputJSON);
Result = 0;
}
else
{
fprintf(stderr, "Usage: %s [haversine_input.json]\n", Args[0]);
fprintf(stderr, " %s [haversine_input.json] [answers.f64]\n", Args[0]);
}
return Result;
}