/*********************************************************/
/*  ptycon: a pty-console bridge                         */
/*  Copyright (C) 2016--2017  SysDeer Technologies, LLC  */
/*  Released under GPLv2 and GPLv3; see COPYING.PTYCON.  */
/*********************************************************/

#include <stddef.h>
#include <ntapi/ntapi.h>
#include "ptycon_memfn_impl.h"
#include "ptycon_driver_impl.h"

void * ptyc_calloc(size_t n, size_t size)
{
	struct ptyc_memory_block block;

	if (!n || (size > (size_t)(-1) / n))
		return 0;

	size *= n;
	size += 0xf;
	size &= ~(size_t)0xf;

	block.addr = 0;
	block.size = size + sizeof(block);

	if (ntapi->zw_allocate_virtual_memory(
			NT_CURRENT_PROCESS_HANDLE,
			&block.addr,
			0,
			&block.size,
			NT_MEM_COMMIT,
			NT_PAGE_READWRITE))
		return 0;

	block.used  = size;
	block.avail = block.size - block.used;

	return (char *)block.addr + offsetof(struct ptyc_memory_block,buffer);
}

void * ptyc_balloc(
	struct ptyc_memory_block * cache,
	struct ptyc_memory_block * block,
	size_t n, size_t size)
{
	char * baddr;
	void * addr = 0;

	if (!n || (size > (size_t)(-1) / n))
		return 0;

	if (!cache || !cache->addr)
		addr = ptyc_calloc(n,size);

	size *= n;
	size += 0xf;
	size &= ~(size_t)0xf;

	if (size < block->avail)
		addr = ptyc_calloc(n,size);

	/* newly allocated block? */
	if (addr) {
		baddr  = addr;
		baddr -= offsetof(struct ptyc_memory_block,buffer);

		ntapi->tt_aligned_block_memcpy(
			(uintptr_t *)block,
			(uintptr_t *)baddr,
			sizeof(*block));

		return addr;
	}

	/* cache */
	addr = &block->buffer[block->used / sizeof(size_t)];
	block->used  += size;
	block->avail -= size;
	return addr;
}

void ptyc_free(void * addr)
{
	struct ptyc_memory_block block;

	block.addr = addr;
	block.size = 0;

	ntapi->zw_free_virtual_memory(
		NT_CURRENT_PROCESS_HANDLE,
		&block.addr,
		&block.size,
		NT_MEM_RELEASE);
}