diff options
author | Julius Werner <jwerner@chromium.org> | 2020-07-01 19:18:34 -0700 |
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committer | Julius Werner <jwerner@chromium.org> | 2020-07-09 00:32:11 +0000 |
commit | 96b00a50f14e3e41eaf69171945ceeb587b4fe0b (patch) | |
tree | e6fb5915dead4c50130fd38977e8830a0fd0d52f /payloads/libpayload/include | |
parent | 56b2550316327efa38d3755128ea8652b1253efb (diff) |
libpayload: Add simple 32.32 fixed-point math API
struct fraction is slooooooooooow. This patch adds a simple 64-bit
(32-bits integral, 32-bits fractional) fixed-point math API that is
*much* faster (observed roughly 5x speed-up) when doing intensive
graphics operations. It is optimized for speed over accuracy so some
operations may lose a bit more precision than expected, but overall it's
still plenty of bits for most use cases.
Also includes support for basic trigonometric functions with a small
lookup table.
Signed-off-by: Julius Werner <jwerner@chromium.org>
Change-Id: Id0f9c23980e36ce0ac0b7c5cd0bc66153bca1fd0
Reviewed-on: https://review.coreboot.org/c/coreboot/+/42993
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Diffstat (limited to 'payloads/libpayload/include')
-rw-r--r-- | payloads/libpayload/include/fpmath.h | 234 |
1 files changed, 234 insertions, 0 deletions
diff --git a/payloads/libpayload/include/fpmath.h b/payloads/libpayload/include/fpmath.h new file mode 100644 index 0000000000..48e900402e --- /dev/null +++ b/payloads/libpayload/include/fpmath.h @@ -0,0 +1,234 @@ +/* + * + * Copyright (C) 2020 Google, Inc. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <stdint.h> + +/* + * This file implements operations for a simple 32.32 fixed-point math type. + * This is intended for speed-critical stuff (e.g. graphics) so there are + * intentionally no overflow checks or assertions, and operations are written + * to prefer speed over precision (e.g. multiplying by 1 may lose precision). + * For best results, only use for applications where 16.16 would fit. + */ + +typedef struct { /* wrap in struct to prevent direct access */ + int64_t v; +} fpmath_t; + +#define FPMATH_SHIFT 32 /* define where to place the decimal point */ + +/* Turn an integer into an fpmath_t. */ +static inline fpmath_t fp(int32_t a) +{ + return (fpmath_t){ .v = (int64_t)a << FPMATH_SHIFT }; +} + +/* Create an fpmath_t from a fraction. (numerator / denominator) */ +static inline fpmath_t fpfrac(int32_t numerator, int32_t denominator) +{ + return (fpmath_t){ .v = ((int64_t)numerator << FPMATH_SHIFT) / denominator }; +} + +/* Turn an fpmath_t back into an integer, rounding towards -INF. */ +static inline int32_t fpfloor(fpmath_t a) +{ + return a.v >> FPMATH_SHIFT; +} + +/* Turn an fpmath_t back into an integer, rounding towards nearest. */ +static inline int32_t fpround(fpmath_t a) +{ + return (a.v + ((int64_t)1 << (FPMATH_SHIFT - 1))) >> FPMATH_SHIFT; +} + +/* Turn an fpmath_t back into an integer, rounding towards +INF. */ +static inline int32_t fpceil(fpmath_t a) +{ + return (a.v + ((int64_t)1 << FPMATH_SHIFT) - 1) >> FPMATH_SHIFT; +} + +/* Add two fpmath_t. (a + b) */ +static inline fpmath_t fpadd(fpmath_t a, fpmath_t b) +{ + return (fpmath_t){ .v = a.v + b.v }; +} + +/* Add an fpmath_t and an integer. (a + b) */ +static inline fpmath_t fpaddi(fpmath_t a, int32_t b) +{ + return (fpmath_t){ .v = a.v + ((int64_t)b << FPMATH_SHIFT) }; +} + +/* Subtract one fpmath_t from another. (a + b) */ +static inline fpmath_t fpsub(fpmath_t a, fpmath_t b) +{ + return (fpmath_t){ .v = a.v - b.v }; +} + +/* Subtract an integer from an fpmath_t. (a - b) */ +static inline fpmath_t fpsubi(fpmath_t a, int32_t b) +{ + return (fpmath_t){ .v = a.v - ((int64_t)b << FPMATH_SHIFT) }; +} + +/* Subtract an fpmath_t from an integer. (a - b) */ +static inline fpmath_t fpisub(int32_t a, fpmath_t b) +{ + return (fpmath_t){ .v = ((int64_t)a << FPMATH_SHIFT) - b.v }; +} + +/* Multiply two fpmath_t. (a * b) + Looses 16 bits fractional precision on each. */ +static inline fpmath_t fpmul(fpmath_t a, fpmath_t b) +{ + return (fpmath_t){ .v = (a.v >> (FPMATH_SHIFT/2)) * (b.v >> (FPMATH_SHIFT/2)) }; +} + +/* Multiply an fpmath_t and an integer. (a * b) */ +static inline fpmath_t fpmuli(fpmath_t a, int32_t b) +{ + return (fpmath_t){ .v = a.v * b }; +} + +/* Divide an fpmath_t by another. (a / b) + Truncates integral part of a to 16 bits! Careful with this one! */ +static inline fpmath_t fpdiv(fpmath_t a, fpmath_t b) +{ + return (fpmath_t){ .v = (a.v << (FPMATH_SHIFT/2)) / (b.v >> (FPMATH_SHIFT/2)) }; +} + +/* Divide an fpmath_t by an integer. (a / b) */ +static inline fpmath_t fpdivi(fpmath_t a, int32_t b) +{ + return (fpmath_t){ .v = a.v / b }; +} + +/* Calculate absolute value of an fpmath_t. (ABS(a)) */ +static inline fpmath_t fpabs(fpmath_t a) +{ + return (fpmath_t){ .v = (a.v < 0 ? -a.v : a.v) }; +} + +/* Return true iff two fpmath_t are exactly equal. (a == b) + Like with floats, you probably don't want to use this most of the time. */ +static inline int fpequals(fpmath_t a, fpmath_t b) +{ + return a.v == b.v; +} + +/* Return true iff one fpmath_t is less than another. (a < b) */ +static inline int fpless(fpmath_t a, fpmath_t b) +{ + return a.v < b.v; +} + +/* Return true iff one fpmath_t is more than another. (a > b) */ +static inline int fpmore(fpmath_t a, fpmath_t b) +{ + return a.v > b.v; +} + +/* Return the smaller of two fpmath_t. (MIN(a, b)) */ +static inline fpmath_t fpmin(fpmath_t a, fpmath_t b) +{ + if (a.v < b.v) + return a; + else + return b; +} + +/* Return the larger of two fpmath_t. (MAX(a, b)) */ +static inline fpmath_t fpmax(fpmath_t a, fpmath_t b) +{ + if (a.v > b.v) + return a; + else + return b; +} + +/* Return the constant PI as an fpmath_t. */ +static inline fpmath_t fppi(void) +{ + /* Rounded (uint64_t)(M_PI * (1UL << 60)) to nine hex digits. */ + return (fpmath_t){ .v = 0x3243f6a89 }; +} + +/* + * Returns the "one-based" sine of an fpmath_t, meaning the input is interpreted as if the range + * 0.0-1.0 corresponded to 0.0-PI/2 for radians. This is mostly here as the base primitives for + * the other trig stuff, but it may be useful to use directly if your input value already needs + * to be multiplied by some factor of PI and you want to save the instructions (and precision) + * for multiplying it in just so that the trig functions can divide it right out again. + */ +fpmath_t fpsin1(fpmath_t x); + +/* Returns the "one-based" cosine of an fpmath_t (analogous definition to fpsin1()). */ +static inline fpmath_t fpcos1(fpmath_t x) +{ + return fpsin1(fpaddi(x, 1)); +} + +/* Returns the sine of an fpmath_t interpreted as radians. */ +static inline fpmath_t fpsinr(fpmath_t radians) +{ + return fpsin1(fpdiv(radians, fpdivi(fppi(), 2))); +} + +/* Returns the sine of an fpmath_t interpreted as degrees. */ +static inline fpmath_t fpsind(fpmath_t degrees) +{ + return fpsin1(fpdivi(degrees, 90)); +} + +/* Returns the cosine of an fpmath_t interpreted as radians. */ +static inline fpmath_t fpcosr(fpmath_t radians) +{ + return fpcos1(fpdiv(radians, fpdivi(fppi(), 2))); +} + +/* Returns the cosine of an fpmath_t interpreted as degrees. */ +static inline fpmath_t fpcosd(fpmath_t degrees) +{ + return fpcos1(fpdivi(degrees, 90)); +} + +/* Returns the tangent of an fpmath_t interpreted as radians. + No guard rails, don't call this at the poles or you'll divide by 0! */ +static inline fpmath_t fptanr(fpmath_t radians) +{ + fpmath_t one_based = fpdiv(radians, fpdivi(fppi(), 2)); + return fpdiv(fpsin1(one_based), fpcos1(one_based)); +} + +/* Returns the tangent of an fpmath_t interpreted as degrees. + No guard rails, don't call this at the poles or you'll divide by 0! */ +static inline fpmath_t fptand(fpmath_t degrees) +{ + fpmath_t one_based = fpdivi(degrees, 90); + return fpdiv(fpsin1(one_based), fpcos1(one_based)); +} |