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pcm.c

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+/*
+ * Copyright 2008-2013 Various Authors
+ * Copyright 2004 Timo Hirvonen
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "pcm.h"
+#include "utils.h"
+
+#include <stdint.h>
+#include <stdlib.h>
+
+/*
+ * Functions to convert PCM to 16-bit signed little-endian stereo
+ *
+ * Conversion for 8-bit PCM):
+ *   1. phase
+ *      unsigned -> signed
+ *      mono -> stereo
+ *      8 -> 16
+ *
+ * Conversion for 16-bit PCM:
+ *   1. phase
+ *      be -> le
+ *      unsigned -> signed
+ *
+ *   2. phase
+ *      mono -> stereo
+ *
+ * There's no reason to split 8-bit conversion to 2 phases because we need to
+ * use separate buffer for 8->16 conversion anyway.
+ *
+ * Conversions for 16-bit stereo can be done in place. 16-bit mono needs to be
+ * converted to stereo so it's worthwhile to split the conversion to 2 phases.
+ */
+
+static void convert_u8_1ch_to_s16_2ch(void *dst, const void *src, int count)
+{
+	int16_t *d = dst;
+	const uint8_t *s = src;
+	int i, j = 0;
+
+	for (i = 0; i < count; i++) {
+		int16_t sample = s[i] << 8;
+		sample -= 32768;
+		d[j++] = sample;
+		d[j++] = sample;
+	}
+}
+
+static void convert_s8_1ch_to_s16_2ch(void *dst, const void *src, int count)
+{
+	int16_t *d = dst;
+	const int8_t *s = src;
+	int i, j = 0;
+
+	for (i = 0; i < count; i++) {
+		int16_t sample = s[i] << 8;
+		d[j++] = sample;
+		d[j++] = sample;
+	}
+}
+
+static void convert_u8_2ch_to_s16_2ch(void *dst, const void *src, int count)
+{
+	int16_t *d = dst;
+	const int8_t *s = src;
+	int i;
+
+	for (i = 0; i < count; i++) {
+		int16_t sample = s[i] << 8;
+		sample -= 32768;
+		d[i] = sample;
+	}
+}
+
+static void convert_s8_2ch_to_s16_2ch(void *dst, const void *src, int count)
+{
+	int16_t *d = dst;
+	const int8_t *s = src;
+	int i;
+
+	for (i = 0; i < count; i++) {
+		int16_t sample = s[i] << 8;
+		d[i] = sample;
+	}
+}
+
+static void convert_u16_le_to_s16_le(void *buf, int count)
+{
+	int16_t *b = buf;
+	int i;
+
+	for (i = 0; i < count; i++) {
+		int sample = (uint16_t)b[i];
+		sample -= 32768;
+		b[i] = sample;
+	}
+}
+
+static void convert_u16_be_to_s16_le(void *buf, int count)
+{
+	int16_t *b = buf;
+	int i;
+
+	for (i = 0; i < count; i++) {
+		uint16_t u = b[i];
+		int sample;
+
+		u = swap_uint16(u);
+		sample = (int)u - 32768;
+		b[i] = sample;
+	}
+}
+
+static void swap_s16_byte_order(void *buf, int count)
+{
+	int16_t *b = buf;
+	int i;
+
+	for (i = 0; i < count; i++)
+		b[i] = swap_uint16(b[i]);
+}
+
+static void convert_16_1ch_to_16_2ch(void *dst, const void *src, int count)
+{
+	int16_t *d = dst;
+	const int16_t *s = src;
+	int i, j = 0;
+
+	for (i = 0; i < count; i++) {
+		d[j++] = s[i];
+		d[j++] = s[i];
+	}
+}
+
+/* index is ((bits >> 2) & 4) | (is_signed << 1) | (channels - 1) */
+pcm_conv_func pcm_conv[8] = {
+	convert_u8_1ch_to_s16_2ch,
+	convert_u8_2ch_to_s16_2ch,
+	convert_s8_1ch_to_s16_2ch,
+	convert_s8_2ch_to_s16_2ch,
+
+	convert_16_1ch_to_16_2ch,
+	NULL,
+	convert_16_1ch_to_16_2ch,
+	NULL
+};
+
+/* index is ((bits >> 2) & 4) | (is_signed << 1) | bigendian */
+pcm_conv_in_place_func pcm_conv_in_place[8] = {
+	NULL,
+	NULL,
+	NULL,
+	NULL,
+
+	convert_u16_le_to_s16_le,
+	convert_u16_be_to_s16_le,
+
+#ifdef WORDS_BIGENDIAN
+	swap_s16_byte_order,
+	NULL,
+#else
+	NULL,
+	swap_s16_byte_order,
+#endif
+};