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pvr: util: Add integer digit counting functions
These are (reasonably) fast helpers for computing the number of binary, decimal or hexadecimal digits required to represent a given non-negative integer. Signed-off-by: Matt Coster <matt.coster@imgtec.com> Reviewed-by: Karmjit Mahil <Karmjit.Mahil@imgtec.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18948>
This commit is contained in:
Matt Coster
Marge Bot
parent
ccac91db7b
commit
f36c938c94
3 changed files with 167 additions and 0 deletions
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@ -24,6 +24,7 @@ libpowervr_common = static_library(
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[
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'pvr_debug.c',
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'pvr_device_info.c',
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'pvr_util.c',
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],
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include_directories : [
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inc_include,
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74
src/imagination/common/pvr_util.c
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74
src/imagination/common/pvr_util.c
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@ -0,0 +1,74 @@
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/*
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* Copyright © 2022 Imagination Technologies Ltd.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#include "pvr_util.h"
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/* Generated by floor(n/log2(10)). This is a compact representation of a
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* log10(2**n) estimation. Estimations of log2(n) +1/-0 are very fast on modern
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* CPUs with clz (or equivalent) instructions, which makes this log2-indexed
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* lookup both compact and fast. Assuming an input of log2(x) +1/-0; this lut
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* should produce an output of ceil(log10(x)) +0/-1.
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*/
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const uint8_t est_log10_from_log2[64 + 1] = {
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0, 0, 0, 0, 1, 1, 1, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4,
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5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 9,
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10, 10, 10, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 14, 14, 14, 15,
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15, 15, 15, 16, 16, 16, 17, 17, 17, 18, 18, 18, 18, 19,
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};
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/* Generated by 10**n with one exception: we make the first power of ten 0
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* (instead of 1) to ensure a 0-input produces a single digit (instead of no
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* digits).
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*/
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const uint32_t u32_powers_of_ten[10] = {
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UINT32_C(0), UINT32_C(10), UINT32_C(100),
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UINT32_C(1000), UINT32_C(10000), UINT32_C(100000),
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UINT32_C(1000000), UINT32_C(10000000), UINT32_C(100000000),
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UINT32_C(1000000000),
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};
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/* This is an extension of u32_powers_of_ten to include all possible 64-bit
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* values.
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*/
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const uint64_t u64_powers_of_ten[20] = {
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UINT64_C(0),
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UINT64_C(10),
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UINT64_C(100),
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UINT64_C(1000),
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UINT64_C(10000),
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UINT64_C(100000),
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UINT64_C(1000000),
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UINT64_C(10000000),
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UINT64_C(100000000),
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UINT64_C(1000000000),
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UINT64_C(10000000000),
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UINT64_C(100000000000),
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UINT64_C(1000000000000),
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UINT64_C(10000000000000),
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UINT64_C(100000000000000),
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UINT64_C(1000000000000000),
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UINT64_C(10000000000000000),
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UINT64_C(100000000000000000),
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UINT64_C(1000000000000000000),
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UINT64_C(10000000000000000000),
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};
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92
src/imagination/common/pvr_util.h
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92
src/imagination/common/pvr_util.h
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@ -0,0 +1,92 @@
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/*
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* Copyright © 2022 Imagination Technologies Ltd.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#ifndef PVR_UTIL_H
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#define PVR_UTIL_H
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#include <stdint.h>
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#include "util/bitscan.h"
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/*****************************************************************************
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Math functions
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*****************************************************************************/
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static inline uint32_t u32_bin_digits(uint32_t x)
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{
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return x == 0 ? 1 : util_last_bit(x);
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}
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static inline uint32_t u64_bin_digits(uint64_t x)
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{
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return x == 0 ? 1 : util_last_bit64(x);
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}
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extern const uint8_t est_log10_from_log2[64 + 1];
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extern const uint32_t u32_powers_of_ten[10];
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extern const uint64_t u64_powers_of_ten[20];
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/*
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* This function includes parts of a public-domain log10 algorithm from
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* "Bit Twiddling Hacks", an aggregate collection which is:
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*
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* © 1997-2005 Sean Eron Anderson.
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*
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* https://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
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*/
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static inline uint32_t u32_dec_digits(uint32_t x)
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{
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/* The value of nr_digits is an estimation of ceil(log10(x)) with variance
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* +0/-1 (as per the comment on the estimation lut).
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*/
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const uint32_t nr_digits = est_log10_from_log2[util_last_bit(x)];
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/* We then convert this approximation to a real value by adding 1 iff
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* x >= 10**nr_digits using another lut to quickly compute the
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* exponentiation. See the comment on u32_powers_of_ten for details of this.
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*/
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return nr_digits + (x >= u32_powers_of_ten[nr_digits]);
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}
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/* This function is an extended form of u32_dec_digits(); see the comments on
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* that function for details.
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*/
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static inline uint32_t u64_dec_digits(uint64_t x)
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{
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const uint32_t nr_digits = est_log10_from_log2[util_last_bit64(x)];
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return nr_digits + (x >= u64_powers_of_ten[nr_digits]);
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}
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static inline uint32_t u32_hex_digits(uint32_t x)
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{
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const uint32_t binary_digits = u32_bin_digits(x);
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return (binary_digits >> 2) + !!(binary_digits & 3);
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}
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static inline uint32_t u64_hex_digits(uint64_t x)
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{
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const uint32_t binary_digits = u64_bin_digits(x);
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return (binary_digits >> 2) + !!(binary_digits & 3);
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}
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#endif /* PVR_UTIL_H */
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