/*
 * AltiVec optimizations for libjpeg-turbo
 *
 * Copyright (C) 2015, D. R. Commander.  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.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 *    claim that you wrote the original software. If you use this software
 *    in a product, an acknowledgment in the product documentation would be
 *    appreciated but is not required.
 * 2. Altered source versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 */

/* CHROMA DOWNSAMPLING */

#include "jsimd_altivec.h"
#include "jcsample.h"


void
jsimd_h2v1_downsample_altivec(JDIMENSION image_width, int max_v_samp_factor,
                              JDIMENSION v_samp_factor,
                              JDIMENSION width_blocks,
                              JSAMPARRAY input_data, JSAMPARRAY output_data) {
	int outrow, outcol;
	JDIMENSION output_cols = width_blocks * DCTSIZE;
	JSAMPROW inptr, outptr;

	__vector unsigned char this0, next0, out;
	__vector unsigned short this0e, this0o, next0e, next0o, outl, outh;

	/* Constants */
	__vector unsigned short pw_bias = {__4X2(0, 1)},
			pw_one = {__8X(1)};
	__vector unsigned char even_odd_index =
			{0, 2, 4, 6, 8, 10, 12, 14, 1, 3, 5, 7, 9, 11, 13, 15},
			pb_zero = {__16X(0)};

	expand_right_edge(input_data, max_v_samp_factor, image_width,
	                  output_cols * 2);

	for (outrow = 0; outrow < v_samp_factor; outrow++) {
		outptr = output_data[outrow];
		inptr = input_data[outrow];

		for (outcol = output_cols; outcol > 0;
		     outcol -= 16, inptr += 32, outptr += 16) {

			this0 = vec_ld(0, inptr);
			this0 = vec_perm(this0, this0, even_odd_index);
			this0e = (__vector unsigned short) VEC_UNPACKHU(this0);
			this0o = (__vector unsigned short) VEC_UNPACKLU(this0);
			outl = vec_add(this0e, this0o);
			outl = vec_add(outl, pw_bias);
			outl = vec_sr(outl, pw_one);

			if (outcol > 8) {
				next0 = vec_ld(16, inptr);
				next0 = vec_perm(next0, next0, even_odd_index);
				next0e = (__vector unsigned short) VEC_UNPACKHU(next0);
				next0o = (__vector unsigned short) VEC_UNPACKLU(next0);
				outh = vec_add(next0e, next0o);
				outh = vec_add(outh, pw_bias);
				outh = vec_sr(outh, pw_one);
			} else
				outh = vec_splat_u16(0);

			out = vec_pack(outl, outh);
			vec_st(out, 0, outptr);
		}
	}
}


void
jsimd_h2v2_downsample_altivec(JDIMENSION image_width, int max_v_samp_factor,
                              JDIMENSION v_samp_factor,
                              JDIMENSION width_blocks,
                              JSAMPARRAY input_data, JSAMPARRAY output_data) {
	int inrow, outrow, outcol;
	JDIMENSION output_cols = width_blocks * DCTSIZE;
	JSAMPROW inptr0, inptr1, outptr;

	__vector unsigned char this0, next0, this1, next1, out;
	__vector unsigned short this0e, this0o, next0e, next0o, this1e, this1o,
			next1e, next1o, out0l, out0h, out1l, out1h, outl, outh;

	/* Constants */
	__vector unsigned short pw_bias = {__4X2(1, 2)},
			pw_two = {__8X(2)};
	__vector unsigned char even_odd_index =
			{0, 2, 4, 6, 8, 10, 12, 14, 1, 3, 5, 7, 9, 11, 13, 15},
			pb_zero = {__16X(0)};

	expand_right_edge(input_data, max_v_samp_factor, image_width,
	                  output_cols * 2);

	for (inrow = 0, outrow = 0; outrow < v_samp_factor;
	     inrow += 2, outrow++) {

		inptr0 = input_data[inrow];
		inptr1 = input_data[inrow + 1];
		outptr = output_data[outrow];

		for (outcol = output_cols; outcol > 0;
		     outcol -= 16, inptr0 += 32, inptr1 += 32, outptr += 16) {

			this0 = vec_ld(0, inptr0);
			this0 = vec_perm(this0, this0, even_odd_index);
			this0e = (__vector unsigned short) VEC_UNPACKHU(this0);
			this0o = (__vector unsigned short) VEC_UNPACKLU(this0);
			out0l = vec_add(this0e, this0o);

			this1 = vec_ld(0, inptr1);
			this1 = vec_perm(this1, this1, even_odd_index);
			this1e = (__vector unsigned short) VEC_UNPACKHU(this1);
			this1o = (__vector unsigned short) VEC_UNPACKLU(this1);
			out1l = vec_add(this1e, this1o);

			outl = vec_add(out0l, out1l);
			outl = vec_add(outl, pw_bias);
			outl = vec_sr(outl, pw_two);

			if (outcol > 8) {
				next0 = vec_ld(16, inptr0);
				next0 = vec_perm(next0, next0, even_odd_index);
				next0e = (__vector unsigned short) VEC_UNPACKHU(next0);
				next0o = (__vector unsigned short) VEC_UNPACKLU(next0);
				out0h = vec_add(next0e, next0o);

				next1 = vec_ld(16, inptr1);
				next1 = vec_perm(next1, next1, even_odd_index);
				next1e = (__vector unsigned short) VEC_UNPACKHU(next1);
				next1o = (__vector unsigned short) VEC_UNPACKLU(next1);
				out1h = vec_add(next1e, next1o);

				outh = vec_add(out0h, out1h);
				outh = vec_add(outh, pw_bias);
				outh = vec_sr(outh, pw_two);
			} else
				outh = vec_splat_u16(0);

			out = vec_pack(outl, outh);
			vec_st(out, 0, outptr);
		}
	}
}
