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-rw-r--r--media/libjpeg/simd/arm/jcgryext-neon.c106
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+/*
+ * jcgryext-neon.c - grayscale colorspace conversion (Arm Neon)
+ *
+ * Copyright (C) 2020, Arm Limited. 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.
+ */
+
+/* This file is included by jcgray-neon.c */
+
+
+/* RGB -> Grayscale conversion is defined by the following equation:
+ * Y = 0.29900 * R + 0.58700 * G + 0.11400 * B
+ *
+ * Avoid floating point arithmetic by using shifted integer constants:
+ * 0.29899597 = 19595 * 2^-16
+ * 0.58700561 = 38470 * 2^-16
+ * 0.11399841 = 7471 * 2^-16
+ * These constants are defined in jcgray-neon.c
+ *
+ * This is the same computation as the RGB -> Y portion of RGB -> YCbCr.
+ */
+
+void jsimd_rgb_gray_convert_neon(JDIMENSION image_width, JSAMPARRAY input_buf,
+ JSAMPIMAGE output_buf, JDIMENSION output_row,
+ int num_rows)
+{
+ JSAMPROW inptr;
+ JSAMPROW outptr;
+ /* Allocate temporary buffer for final (image_width % 16) pixels in row. */
+ ALIGN(16) uint8_t tmp_buf[16 * RGB_PIXELSIZE];
+
+ while (--num_rows >= 0) {
+ inptr = *input_buf++;
+ outptr = output_buf[0][output_row];
+ output_row++;
+
+ int cols_remaining = image_width;
+ for (; cols_remaining > 0; cols_remaining -= 16) {
+
+ /* To prevent buffer overread by the vector load instructions, the last
+ * (image_width % 16) columns of data are first memcopied to a temporary
+ * buffer large enough to accommodate the vector load.
+ */
+ if (cols_remaining < 16) {
+ memcpy(tmp_buf, inptr, cols_remaining * RGB_PIXELSIZE);
+ inptr = tmp_buf;
+ }
+
+#if RGB_PIXELSIZE == 4
+ uint8x16x4_t input_pixels = vld4q_u8(inptr);
+#else
+ uint8x16x3_t input_pixels = vld3q_u8(inptr);
+#endif
+ uint16x8_t r_l = vmovl_u8(vget_low_u8(input_pixels.val[RGB_RED]));
+ uint16x8_t r_h = vmovl_u8(vget_high_u8(input_pixels.val[RGB_RED]));
+ uint16x8_t g_l = vmovl_u8(vget_low_u8(input_pixels.val[RGB_GREEN]));
+ uint16x8_t g_h = vmovl_u8(vget_high_u8(input_pixels.val[RGB_GREEN]));
+ uint16x8_t b_l = vmovl_u8(vget_low_u8(input_pixels.val[RGB_BLUE]));
+ uint16x8_t b_h = vmovl_u8(vget_high_u8(input_pixels.val[RGB_BLUE]));
+
+ /* Compute Y = 0.29900 * R + 0.58700 * G + 0.11400 * B */
+ uint32x4_t y_ll = vmull_n_u16(vget_low_u16(r_l), F_0_298);
+ uint32x4_t y_lh = vmull_n_u16(vget_high_u16(r_l), F_0_298);
+ uint32x4_t y_hl = vmull_n_u16(vget_low_u16(r_h), F_0_298);
+ uint32x4_t y_hh = vmull_n_u16(vget_high_u16(r_h), F_0_298);
+ y_ll = vmlal_n_u16(y_ll, vget_low_u16(g_l), F_0_587);
+ y_lh = vmlal_n_u16(y_lh, vget_high_u16(g_l), F_0_587);
+ y_hl = vmlal_n_u16(y_hl, vget_low_u16(g_h), F_0_587);
+ y_hh = vmlal_n_u16(y_hh, vget_high_u16(g_h), F_0_587);
+ y_ll = vmlal_n_u16(y_ll, vget_low_u16(b_l), F_0_113);
+ y_lh = vmlal_n_u16(y_lh, vget_high_u16(b_l), F_0_113);
+ y_hl = vmlal_n_u16(y_hl, vget_low_u16(b_h), F_0_113);
+ y_hh = vmlal_n_u16(y_hh, vget_high_u16(b_h), F_0_113);
+
+ /* Descale Y values (rounding right shift) and narrow to 16-bit. */
+ uint16x8_t y_l = vcombine_u16(vrshrn_n_u32(y_ll, 16),
+ vrshrn_n_u32(y_lh, 16));
+ uint16x8_t y_h = vcombine_u16(vrshrn_n_u32(y_hl, 16),
+ vrshrn_n_u32(y_hh, 16));
+
+ /* Narrow Y values to 8-bit and store to memory. Buffer overwrite is
+ * permitted up to the next multiple of ALIGN_SIZE bytes.
+ */
+ vst1q_u8(outptr, vcombine_u8(vmovn_u16(y_l), vmovn_u16(y_h)));
+
+ /* Increment pointers. */
+ inptr += (16 * RGB_PIXELSIZE);
+ outptr += 16;
+ }
+ }
+}