/********************************************************/

/*  ntapi: Native API core library                      */

/*  Copyright (C) 2013--2021  SysDeer Technologies, LLC */

/*  Released under GPLv2 and GPLv3; see COPYING.NTAPI.  */

/********************************************************/

#include <psxtypes/psxtypes.h>

#include <ntapi/nt_status.h>

#include <ntapi/nt_unicode.h>

#include "ntapi_impl.h"

typedef struct ___two_bytes {

	unsigned char	low;

	unsigned char	high;

} __two_bytes;

typedef struct ___three_bytes {

	unsigned char	low;

	unsigned char	middle;

	unsigned char	high;

} __three_bytes;

static int32_t __fastcall __utf8_to_utf16_handler_1byte_or_null_termination(nt_utf8_callback_args * args)

{

	/***************************/

	/* from: 0xxxxxxx          */

	/* to:   00000000 0xxxxxxx */

	/***************************/

	wchar16_t *	dst;

	if (args->dst >= args->dst_cap)

		return NT_STATUS_BUFFER_TOO_SMALL;

	dst  = (wchar16_t *)args->dst;

	*dst = *(args->src);

	/* advance source and destination buffer */

	args->src++;

	args->dst = (void *)((uintptr_t)(args->dst) + sizeof(wchar16_t));

	/* bytes_written */

	args->bytes_written += sizeof(wchar16_t);

	return NT_STATUS_SUCCESS;

}

static int32_t __fastcall __utf8_to_utf16_handler_2bytes(nt_utf8_callback_args * args)

{

	/***************************/

	/* from: 110yyyyy 10xxxxxx */

	/* to:   00000yyy yyxxxxxx */

	/***************************/

	__two_bytes *		src; /* big endian */

	wchar16_t *		dst;

	if (args->dst >= args->dst_cap)

		return NT_STATUS_BUFFER_TOO_SMALL;

	src	= (__two_bytes *)args->src;

	dst	= (wchar16_t *)args->dst;

	/* yyyyy */

	*dst   = (src->low ^ 0xC0);

	*dst <<= 6;

	/* xxxxxx */

	*dst |= (src->high  ^ 0x80);

	/* advance source and destination buffer */

	args->src += 2;

	args->dst = (void *)((uintptr_t)(args->dst) + sizeof(wchar16_t));

	/* bytes_written */

	args->bytes_written += sizeof(wchar16_t);

	return NT_STATUS_SUCCESS;

}

static int32_t __fastcall __utf8_to_utf16_handler_3bytes(nt_utf8_callback_args * args)

{

	/************************************/

	/* from: 1110zzzz 10yyyyyy 10xxxxxx */

	/* to:   zzzzyyyy yyxxxxxx          */

	/************************************/

	__three_bytes *		src; /* big endian */

	wchar16_t *		dst;

	wchar16_t		yyyyy;

	if (args->dst >= args->dst_cap)

		return NT_STATUS_BUFFER_TOO_SMALL;

	src	= (__three_bytes *)args->src;

	dst	= (wchar16_t *)args->dst;

	/* zzzz */

	*dst   = (src->low ^ 0xE0);

	*dst <<= 12;

	/* yyyyy */

	yyyyy   = (src->middle ^ 0x80);

	yyyyy <<= 6;

	*dst |= yyyyy;

	/* xxxxxx */

	*dst |= (src->high ^ 0x80);

	/* advance source and destination buffer */

	args->src += 3;

	args->dst = (void *)((uintptr_t)(args->dst) + sizeof(wchar16_t));

	/* bytes_written */

	args->bytes_written += sizeof(wchar16_t);

	return NT_STATUS_SUCCESS;

}

static int32_t __fastcall __utf8_to_utf16_handler_4bytes(nt_utf8_callback_args * args)

{

	/*************************************************/

	/* from: 11110uuu  10uuzzzz  10yyyyyy  10xxxxxx  */

	/* to:   110110ww  wwzzzzyy  110111yy  yyxxxxxx  */

	/*************************************************/

	__two_bytes *		src_low;	/* big endian */

	__two_bytes *		src_high;	/* big endian */

	wchar16_t *		dst_lead;

	wchar16_t *		dst_trail;

	wchar16_t		wwww;

	wchar16_t		lead;

	wchar16_t		trail;

	unsigned char		ulow;

	unsigned char		uhigh;

	unsigned char		yy;

	unsigned char		yyyy;

	unsigned char		zzzz;

	dst_lead = dst_trail = (wchar16_t *)args->dst;

	dst_trail++;

	if ((uintptr_t)dst_trail >= (uintptr_t)args->dst_cap)

		return NT_STATUS_BUFFER_TOO_SMALL;

	src_low	= src_high = (__two_bytes *)args->src;

	src_high++;

	/* uuuuu */

	ulow	= src_low->low  ^ 0xF0;

	uhigh	= src_low->high ^ 0x80;

	ulow  <<= 2;

	uhigh >>= 4;

	/* wwww */

	wwww   = (ulow | uhigh) - 1;

	wwww <<= 6;

	/* 110110ww wwzzzzyy */

	yy     = src_high->low ^ 0x80;

	yy   >>= 4;

	zzzz   = src_low->high;

	zzzz <<= 4;

	zzzz >>= 2;

	lead   = 0xD800;

	lead  |= wwww;

	lead  |= zzzz;

	lead  |= yy;

	/* 110111yy  yyxxxxxx */

	yyyy   = src_high->low << 4;

	trail  = yyyy << 2;

	trail |= src_high->high ^ 0x80;

	trail |= 0xDC00;

	/* write */

	*dst_lead  = lead;

	*dst_trail = trail;

	/* advance source and destination buffer */

	args->src += 4;

	args->dst = (void *)((uintptr_t)(args->dst) + (2 * sizeof(wchar16_t)));

	/* bytes_written */

	args->bytes_written += 2 * sizeof(wchar16_t);

	return NT_STATUS_SUCCESS;

}

static int32_t __fastcall __update_stream_leftover_info_utf8(

	__in_out	nt_unicode_conversion_params_utf8_to_utf16 *	params)

{

	int32_t		status;

	ptrdiff_t	offset;

	unsigned char *	utf8;

	offset	= (uintptr_t)params->src + (uintptr_t)params->src_size_in_bytes - (uintptr_t)params->addr_failed;

	utf8	= (unsigned char *)params->addr_failed;

	/* default status */

	status	= NT_STATUS_ILLEGAL_CHARACTER;

	if (offset == 1) {

		if ((utf8[0] >= 0xC2) && (utf8[0] <= 0xF4)) {

			/* one leftover byte */

			params->leftover_count = 1;

			params->leftover_bytes = utf8[0];

			params->leftover_bytes <<= 24;

			status = NT_STATUS_SUCCESS;

		}

	} else 	if (offset == 2) {

		if /* ------- */  (((utf8[0] == 0xE0) &&                      (utf8[1] >= 0xA0) && (utf8[1] <= 0xBF))

				|| ((utf8[0] >= 0xE1) && (utf8[0] <= 0xEC) && (utf8[1] >= 0x80) && (utf8[1] <= 0xBF))

				|| ((utf8[0] == 0xED) &&                      (utf8[1] >= 0x80) && (utf8[1] <= 0x9F))

				|| ((utf8[0] >= 0xEE) && (utf8[0] <= 0xEF) && (utf8[1] >= 0x80) && (utf8[1] <= 0xBF))

				|| ((utf8[0] == 0xF0) &&                      (utf8[1] >= 0x90) && (utf8[1] <= 0xBF))

				|| ((utf8[0] >= 0xF1) && (utf8[0] <= 0xF3) && (utf8[1] >= 0x80) && (utf8[1] <= 0xBF))

				|| ((utf8[0] == 0xF4) &&                      (utf8[1] >= 0x80) && (utf8[1] <= 0x8F))) {

			/* two leftover bytes */

			params->leftover_count = 2;

			params->leftover_bytes = utf8[0];

			params->leftover_bytes <<= 8;

			params->leftover_bytes += utf8[1];

			params->leftover_bytes <<= 16;

			status = NT_STATUS_SUCCESS;

		}

	} else if (offset == 3) {

		if /* ------- */  (((utf8[0] == 0xF0) &&                      (utf8[1] >= 0x90) && (utf8[1] <= 0xBF))

				|| ((utf8[0] >= 0xF1) && (utf8[0] <= 0xF3) && (utf8[1] >= 0x80) && (utf8[1] <= 0xBF))

				|| ((utf8[0] == 0xF4) &&                      (utf8[1] >= 0x80) && (utf8[1] <= 0x8F))) {

			/* three leftover bytes */

			params->leftover_count = 3;

			params->leftover_bytes = utf8[0];

			params->leftover_bytes <<= 8;

			params->leftover_bytes += utf8[1];

			params->leftover_bytes <<= 8;

			params->leftover_bytes += utf8[2];

			params->leftover_bytes <<= 8;

			status = NT_STATUS_SUCCESS;

		}

	}

	if (status != NT_STATUS_SUCCESS) {

		params->leftover_count = 0;

		params->leftover_bytes = 0;

	}

	return status;

}

int32_t __stdcall 	__ntapi_uc_convert_unicode_stream_utf8_to_utf16(

	__in_out	nt_unicode_conversion_params_utf8_to_utf16 *	params)

{

	int32_t 			status;

	nt_utf8_callback_args		args;

	ntapi_uc_utf8_callback_fn *	callback_fn[5];

	callback_fn[0] = (ntapi_uc_utf8_callback_fn *)__utf8_to_utf16_handler_1byte_or_null_termination;

	callback_fn[1] = (ntapi_uc_utf8_callback_fn *)__utf8_to_utf16_handler_1byte_or_null_termination;

	callback_fn[2] = (ntapi_uc_utf8_callback_fn *)__utf8_to_utf16_handler_2bytes;

	callback_fn[3] = (ntapi_uc_utf8_callback_fn *)__utf8_to_utf16_handler_3bytes;

	callback_fn[4] = (ntapi_uc_utf8_callback_fn *)__utf8_to_utf16_handler_4bytes;

	args.src		= params->src;

	args.dst		= params->dst;

	args.dst_cap		= (void *)((uintptr_t)(params->dst) + (params->dst_size_in_bytes));

	args.bytes_written	= params->bytes_written;

	status = __ntapi_uc_validate_unicode_stream_utf8(

		params->src,

		params->src_size_in_bytes,

		&params->code_points,

		&params->addr_failed,

		callback_fn,

		&args);

	params->bytes_written = args.bytes_written;

	switch (status) {

		case NT_STATUS_SUCCESS:

			params->addr_failed    = 0;

			params->leftover_bytes = 0;

			params->leftover_count = 0;

			return status;

		case NT_STATUS_BUFFER_TOO_SMALL:

			params->addr_failed    = args.src;

			params->leftover_bytes = 0;

			params->leftover_count = 0;

			return status;

		default:

			status = __update_stream_leftover_info_utf8(params);

	}

	/* (optimized out on 32-bit architectures) */

	params->leftover_bytes <<= (8 * (sizeof(uintptr_t) - sizeof(uint32_t)));

	return status;

}

int32_t __stdcall 	__ntapi_uc_convert_unicode_stream_utf8_to_utf32(

	__in_out	nt_unicode_conversion_params_utf8_to_utf32 *	params)

{

	(void)params;

	return NT_STATUS_SUCCESS;

}