diff options
| -rw-r--r-- | drivers/sound/Kconfig | 13 | ||||
| -rw-r--r-- | drivers/sound/Makefile | 2 | ||||
| -rw-r--r-- | drivers/sound/synth.c | 43 | ||||
| -rw-r--r-- | include/linux/fixp-arith.h | 144 | ||||
| -rw-r--r-- | include/sound.h | 32 |
5 files changed, 233 insertions, 1 deletions
diff --git a/drivers/sound/Kconfig b/drivers/sound/Kconfig index cce5c760af..d9f63a5f3c 100644 --- a/drivers/sound/Kconfig +++ b/drivers/sound/Kconfig @@ -6,3 +6,16 @@ menuconfig SOUND Say Y here for sound support. At the moment that's just beep tones. Tones are played asynchronously in a poller. Check the beep command for how to exercise the API. + +if SOUND + +config SYNTH_SQUARES + bool "Synthesize square waves only" + help + For beeping on PCM sound cards, barebox needs to synthesize samples, + which can take too much poller time for crisp playback and/or quick + booting. If your playback stutters, say Y here. This will have all + synthesizers output a gain-adjusted square wave instead, which is + less time-consuming to compute. + +endif diff --git a/drivers/sound/Makefile b/drivers/sound/Makefile index e343e0fa72..69873faab9 100644 --- a/drivers/sound/Makefile +++ b/drivers/sound/Makefile @@ -1,2 +1,2 @@ # SPDX-License-Identifier: GPL-2.0-only -obj-y += core.o +obj-y += core.o synth.o diff --git a/drivers/sound/synth.c b/drivers/sound/synth.c new file mode 100644 index 0000000000..c9de62b516 --- /dev/null +++ b/drivers/sound/synth.c @@ -0,0 +1,43 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2012 Samsung Electronics, R. Chandrasekar <rcsekar@samsung.com> + * Copyright (C) 2021 Ahmad Fatoum + */ + +#include <common.h> +#include <linux/fixp-arith.h> +#include <linux/math64.h> +#include <sound.h> + +void __synth_sin(unsigned freq, s16 amplitude, s16 *stream, + unsigned sample_rate, unsigned nsamples) +{ + int64_t v = 0; + int i = 0; + + for (i = 0; i < nsamples; i++) { + /* Assume RHS sign extension, true for GCC */ + stream[i] = (fixp_sin32(div_s64(v * 360, sample_rate)) * (int64_t)amplitude) >> 31; + v += freq; + } +} + +void __synth_square(unsigned freq, s16 amplitude, s16 *stream, + unsigned sample_rate, unsigned nsamples) +{ + unsigned period = freq ? sample_rate / freq : 0; + int half = period / 2; + + while (nsamples) { + int i; + + for (i = 0; nsamples && i < half; i++) { + nsamples--; + *stream++ = amplitude; + } + for (i = 0; nsamples && i < period - half; i++) { + nsamples--; + *stream++ = -amplitude; + } + } +} diff --git a/include/linux/fixp-arith.h b/include/linux/fixp-arith.h new file mode 100644 index 0000000000..8396013785 --- /dev/null +++ b/include/linux/fixp-arith.h @@ -0,0 +1,144 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +#ifndef _FIXP_ARITH_H +#define _FIXP_ARITH_H + +#include <linux/math64.h> + +/* + * Simplistic fixed-point arithmetics. + * Hmm, I'm probably duplicating some code :( + * + * Copyright (c) 2002 Johann Deneux + */ + +/* + * + * Should you need to contact me, the author, you can do so by + * e-mail - mail your message to <johann.deneux@gmail.com> + */ + +#include <linux/types.h> + +static const s32 sin_table[] = { + 0x00000000, 0x023be165, 0x04779632, 0x06b2f1d2, 0x08edc7b6, 0x0b27eb5c, + 0x0d61304d, 0x0f996a26, 0x11d06c96, 0x14060b67, 0x163a1a7d, 0x186c6ddd, + 0x1a9cd9ac, 0x1ccb3236, 0x1ef74bf2, 0x2120fb82, 0x234815ba, 0x256c6f9e, + 0x278dde6e, 0x29ac379f, 0x2bc750e8, 0x2ddf003f, 0x2ff31bdd, 0x32037a44, + 0x340ff241, 0x36185aee, 0x381c8bb5, 0x3a1c5c56, 0x3c17a4e7, 0x3e0e3ddb, + 0x3fffffff, 0x41ecc483, 0x43d464fa, 0x45b6bb5d, 0x4793a20f, 0x496af3e1, + 0x4b3c8c11, 0x4d084650, 0x4ecdfec6, 0x508d9210, 0x5246dd48, 0x53f9be04, + 0x55a6125a, 0x574bb8e5, 0x58ea90c2, 0x5a827999, 0x5c135399, 0x5d9cff82, + 0x5f1f5ea0, 0x609a52d1, 0x620dbe8a, 0x637984d3, 0x64dd894f, 0x6639b039, + 0x678dde6d, 0x68d9f963, 0x6a1de735, 0x6b598ea1, 0x6c8cd70a, 0x6db7a879, + 0x6ed9eba0, 0x6ff389de, 0x71046d3c, 0x720c8074, 0x730baeec, 0x7401e4bf, + 0x74ef0ebb, 0x75d31a5f, 0x76adf5e5, 0x777f903b, 0x7847d908, 0x7906c0af, + 0x79bc384c, 0x7a6831b8, 0x7b0a9f8c, 0x7ba3751c, 0x7c32a67c, 0x7cb82884, + 0x7d33f0c8, 0x7da5f5a3, 0x7e0e2e31, 0x7e6c924f, 0x7ec11aa3, 0x7f0bc095, + 0x7f4c7e52, 0x7f834ecf, 0x7fb02dc4, 0x7fd317b3, 0x7fec09e1, 0x7ffb025e, + 0x7fffffff +}; + +/** + * __fixp_sin32() returns the sin of an angle in degrees + * + * @degrees: angle, in degrees, from 0 to 360. + * + * The returned value ranges from -0x7fffffff to +0x7fffffff. + */ +static inline s32 __fixp_sin32(int degrees) +{ + s32 ret; + bool negative = false; + + if (degrees > 180) { + negative = true; + degrees -= 180; + } + if (degrees > 90) + degrees = 180 - degrees; + + ret = sin_table[degrees]; + + return negative ? -ret : ret; +} + +/** + * fixp_sin32() returns the sin of an angle in degrees + * + * @degrees: angle, in degrees. The angle can be positive or negative + * + * The returned value ranges from -0x7fffffff to +0x7fffffff. + */ +static inline s32 fixp_sin32(int degrees) +{ + degrees = (degrees % 360 + 360) % 360; + + return __fixp_sin32(degrees); +} + +/* cos(x) = sin(x + 90 degrees) */ +#define fixp_cos32(v) fixp_sin32((v) + 90) + +/* + * 16 bits variants + * + * The returned value ranges from -0x7fff to 0x7fff + */ + +#define fixp_sin16(v) (fixp_sin32(v) >> 16) +#define fixp_cos16(v) (fixp_cos32(v) >> 16) + +/** + * fixp_sin32_rad() - calculates the sin of an angle in radians + * + * @radians: angle, in radians + * @twopi: value to be used for 2*pi + * + * Provides a variant for the cases where just 360 + * values is not enough. This function uses linear + * interpolation to a wider range of values given by + * twopi var. + * + * Experimental tests gave a maximum difference of + * 0.000038 between the value calculated by sin() and + * the one produced by this function, when twopi is + * equal to 360000. That seems to be enough precision + * for practical purposes. + * + * Please notice that two high numbers for twopi could cause + * overflows, so the routine will not allow values of twopi + * bigger than 1^18. + */ +static inline s32 fixp_sin32_rad(u32 radians, u32 twopi) +{ + int degrees; + s32 v1, v2, dx, dy; + s64 tmp; + + /* + * Avoid too large values for twopi, as we don't want overflows. + */ + BUG_ON(twopi > 1 << 18); + + degrees = (radians * 360) / twopi; + tmp = radians - (degrees * twopi) / 360; + + degrees = (degrees % 360 + 360) % 360; + v1 = __fixp_sin32(degrees); + + v2 = fixp_sin32(degrees + 1); + + dx = twopi / 360; + dy = v2 - v1; + + tmp *= dy; + + return v1 + div_s64(tmp, dx); +} + +/* cos(x) = sin(x + pi/2 radians) */ + +#define fixp_cos32_rad(rad, twopi) \ + fixp_sin32_rad(rad + twopi / 4, twopi) + +#endif diff --git a/include/sound.h b/include/sound.h index f5124aebbd..62fef106ee 100644 --- a/include/sound.h +++ b/include/sound.h @@ -42,4 +42,36 @@ static inline int beep_cancel(void) return sound_card_beep_cancel(sound_card_get_default()); } + +/* + * Synthesizers all have the same prototype, but their implementation + * is replaced with a gain-adjusted square wave if CONFIG_SYNTH_SQUARES=y. + * This is to support PCM beeping on systems, where sine generation may + * spend to much time in the poller. + */ +typedef void synth_t(unsigned freq, s16 amplitude, s16 *stream, + unsigned sample_rate, unsigned nsamples); + +#ifdef CONFIG_SYNTH_SQUARES +#define SYNTH(fn, volume_percent) \ + static inline void fn(unsigned f, s16 amplitude, s16 *s, \ + unsigned r, unsigned n) { \ + synth_t __synth_square; \ + amplitude = amplitude * volume_percent / 100; \ + __synth_square(f, amplitude, s, r, n); \ + } \ + synth_t __##fn +#else +#define SYNTH(fn, volume_percent) \ + static inline void fn(unsigned f, s16 a, s16 *s, \ + unsigned r, unsigned n) { \ + synth_t __##fn; \ + __##fn(f, a, s, r, n); \ + } \ + synth_t __##fn +#endif + +SYNTH(synth_square, 100); /* square wave always has full amplitude */ +SYNTH(synth_sin, 64); /* ∫₀¹ sin(πx) dx ≈ 64% */ + #endif |