stn_memory.h

/*
   stn_memory.h - v1.1.0

   ----------------------------------------------------------------------------

   MIT License

   Copyright (c) 2021 Nullsson

   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.
*/

#ifndef STN_MEMORY_H
#define STN_MEMORY_H

// TODO(Oskar): Add support for memory pools.
// TODO(Oskar): Add supprot for stack based arena.

typedef struct memory_arena memory_arena;
struct memory_arena
{
    void *Memory;
    u32 MemorySize;
    u32 MemoryAllocPosition;
    u32 MemoryLeft;
    u32 MinimumAlignment;
};

STN_INTERNAL memory_arena
#ifdef STN_LANGUAGE_C
MemoryArenaInit(void *Memory, u32 MemorySize, u32 Alignment)
#else
MemoryArenaInit(void *Memory, u32 MemorySize, u32 Alignment = 8)
#endif
{
    memory_arena Arena = {0};

    Arena.Memory = Memory;
    Arena.MemorySize = MemorySize;
    Arena.MemoryLeft = MemorySize;
    Arena.MinimumAlignment = Alignment;

    return (Arena);
}

STN_INTERNAL void *
#ifdef STN_LANGUAGE_C
MemoryArenaAllocate(memory_arena *Arena, u32 Size, u32 Alignment)
#else
MemoryArenaAllocate(memory_arena *Arena, u32 Size, u32 Alignment = 1)
#endif
{
    void *Memory = 0;

    if (Alignment < Arena->MinimumAlignment)
    {
        Alignment = Arena->MinimumAlignment;
    }

    if (Arena->MemoryAllocPosition + Size <= Arena->MemorySize)
    {
        Memory = (void *)((char *)Arena->Memory+Arena->MemoryAllocPosition);
        u32 BytesOffAlignment = (uintptr_t)Memory % (uintptr_t)Alignment;
        if (BytesOffAlignment != 0)
        {
            u32 Padding = Alignment - BytesOffAlignment;
            Memory = (char *)Memory + Padding;
            Size += Padding;
        }

        Arena->MemoryAllocPosition += Size;
        Arena->MemoryLeft -= Size;
    }

    return (Memory);
}

STN_INTERNAL void *
#ifdef STN_LANGUAGE_C
MemoryArenaAllocateAndZero(memory_arena *Arena, u32 Size, u32 Alignment)
#else
MemoryArenaAllocateAndZero(memory_arena *Arena, u32 Size, u32 Alignment = 1)
#endif
{
    void *Memory = MemoryArenaAllocate(Arena, Size, Alignment);
    if (Memory)
    {
        MemorySet(Memory, 0, Size);
    }

    return (Memory);
}

STN_INTERNAL void
MemoryArenaFreeBytes(memory_arena *Arena, u32 Size)
{
    if (Size > Arena->MemoryAllocPosition)
    {
        Arena->MemoryAllocPosition = 0;
        Arena->MemoryLeft = Arena->MemorySize;
    }
    else
    {
        Arena->MemoryAllocPosition -= Size;
        Arena->MemoryLeft += Size;
    }
}

STN_INTERNAL void
MemoryArenaClear(memory_arena *Arena)
{
    Arena->MemoryAllocPosition = 0;
    Arena->MemoryLeft = Arena->MemorySize;
}

STN_INTERNAL void
MemoryArenaZero(memory_arena *Arena)
{
    MemorySet(Arena->Memory, 0, Arena->MemorySize);
}

STN_INTERNAL char *
MemoryArenaAllocateCStringCopy(memory_arena *Arena, char *String)
{
    u32 StringLength = CalculateCStringLength(String);
    char *StringCopy = (char *)MemoryArenaAllocate(Arena, StringLength+1, 1);
    
    if(StringCopy)
    {
        MemoryCopy(StringCopy, String, StringLength);
        StringCopy[StringLength] = 0;
    }
    
    return (StringCopy);
}

STN_INTERNAL b32
MemoryArenaWrite(memory_arena *Arena, void *Source, u32 Size)
{
    b32 Success = 0;
    
    if (Arena->MemoryLeft >= Size)
    {
        void *Destination = MemoryArenaAllocate(Arena, Size, 1);
        MemoryCopy(Destination, Source, Size);
        Success = 1;
    }

    return (Success);
}

STN_INTERNAL b32
MemoryArenaRead(memory_arena *Arena, void *Destination, u32 Size)
{
    b32 Success = 0;

    if (Arena->MemoryLeft >= Size)
    {
        void *Source = MemoryArenaAllocate(Arena, Size, 1);
        MemoryCopy(Destination, Source, Size);
        Success = 1;
    }

    return (Success);
}

#if defined(STN_USE_ALL) || defined(STN_USE_STRING)
STN_INTERNAL string
MakeStringOnMemoryArena(memory_arena *Arena, char *Format, ...)
{
    string String = {0};

    va_list Args;
    va_start(Args, Format);
    u32 NeededBytes = vsnprintf(0, 0, Format, Args) + 1;
    va_end(Args);

    String.Data = (char *)MemoryArenaAllocate(Arena, NeededBytes, 1);
    
    if (String.Data)
    {
        String.Length = NeededBytes - 1;
        String.Size = NeededBytes;
        String.MaxSize = String.Size;
        String.IsMutable = 0;

        va_start(Args, Format);
        vsnprintf(String.Data, NeededBytes, Format, Args);
        va_end(Args);

        String.Data[NeededBytes - 1] = 0;
    }

    return (String);
}
#endif // defined(STN_USE_ALL) || defined(STN_USE_STRING)

#endif // STN_MEMORY_H