diff --git a/Documentation/core-api/kernel-api.rst b/Documentation/core-api/kernel-api.rst index f2bcc5a7ea43..a526fbe06f86 100644 --- a/Documentation/core-api/kernel-api.rst +++ b/Documentation/core-api/kernel-api.rst @@ -162,8 +162,11 @@ Base 2 log and power Functions .. kernel-doc:: include/linux/log2.h :internal: -Integer power Functions ------------------------ +Integer log and power Functions +------------------------------- + +.. kernel-doc:: include/linux/int_log.h + :export: .. kernel-doc:: lib/math/int_pow.c :export: diff --git a/Documentation/driver-api/media/dtv-common.rst b/Documentation/driver-api/media/dtv-common.rst index f8b2c4dc8170..207a22bcaf4a 100644 --- a/Documentation/driver-api/media/dtv-common.rst +++ b/Documentation/driver-api/media/dtv-common.rst @@ -3,15 +3,6 @@ Digital TV Common functions --------------------------- -Math functions -~~~~~~~~~~~~~~ - -Provide some commonly-used math functions, usually required in order to -estimate signal strength and signal to noise measurements in dB. - -.. kernel-doc:: include/media/dvb_math.h - - DVB devices ~~~~~~~~~~~ diff --git a/drivers/media/dvb-core/Makefile b/drivers/media/dvb-core/Makefile index 62b028ded9f7..1cb3ca67bed9 100644 --- a/drivers/media/dvb-core/Makefile +++ b/drivers/media/dvb-core/Makefile @@ -8,6 +8,6 @@ dvb-vb2-$(CONFIG_DVB_MMAP) := dvb_vb2.o dvb-core-objs := dvbdev.o dmxdev.o dvb_demux.o \ dvb_ca_en50221.o dvb_frontend.o \ - $(dvb-net-y) dvb_ringbuffer.o $(dvb-vb2-y) dvb_math.o + $(dvb-net-y) dvb_ringbuffer.o $(dvb-vb2-y) obj-$(CONFIG_DVB_CORE) += dvb-core.o diff --git a/drivers/media/dvb-frontends/af9013_priv.h b/drivers/media/dvb-frontends/af9013_priv.h index 3b9b9424fe1a..bba7a9693a23 100644 --- a/drivers/media/dvb-frontends/af9013_priv.h +++ b/drivers/media/dvb-frontends/af9013_priv.h @@ -12,7 +12,7 @@ #define AF9013_PRIV_H #include -#include +#include #include "af9013.h" #include #include diff --git a/drivers/media/dvb-frontends/af9033_priv.h b/drivers/media/dvb-frontends/af9033_priv.h index 0e64da0cdeab..7560da75ef00 100644 --- a/drivers/media/dvb-frontends/af9033_priv.h +++ b/drivers/media/dvb-frontends/af9033_priv.h @@ -14,7 +14,7 @@ #include #include #include -#include +#include struct reg_val { u32 reg; diff --git a/drivers/media/dvb-frontends/cxd2820r_priv.h b/drivers/media/dvb-frontends/cxd2820r_priv.h index 9b4d9cf8563d..605320bbc12b 100644 --- a/drivers/media/dvb-frontends/cxd2820r_priv.h +++ b/drivers/media/dvb-frontends/cxd2820r_priv.h @@ -11,7 +11,7 @@ #include #include -#include +#include #include "cxd2820r.h" #include /* For gpio_chip */ #include diff --git a/drivers/media/dvb-frontends/cxd2841er.c b/drivers/media/dvb-frontends/cxd2841er.c index 5431f922f55e..ef403a9fb753 100644 --- a/drivers/media/dvb-frontends/cxd2841er.c +++ b/drivers/media/dvb-frontends/cxd2841er.c @@ -22,7 +22,7 @@ #include #include -#include +#include #include #include "cxd2841er.h" #include "cxd2841er_priv.h" diff --git a/drivers/media/dvb-frontends/cxd2880/cxd2880_tnrdmd_dvbt2_mon.c b/drivers/media/dvb-frontends/cxd2880/cxd2880_tnrdmd_dvbt2_mon.c index 604580bf7cf7..4e173dd87ecf 100644 --- a/drivers/media/dvb-frontends/cxd2880/cxd2880_tnrdmd_dvbt2_mon.c +++ b/drivers/media/dvb-frontends/cxd2880/cxd2880_tnrdmd_dvbt2_mon.c @@ -11,7 +11,7 @@ #include "cxd2880_tnrdmd_dvbt2.h" #include "cxd2880_tnrdmd_dvbt2_mon.h" -#include +#include static const int ref_dbm_1000[4][8] = { {-96000, -95000, -94000, -93000, -92000, -92000, -98000, -97000}, diff --git a/drivers/media/dvb-frontends/cxd2880/cxd2880_tnrdmd_dvbt_mon.c b/drivers/media/dvb-frontends/cxd2880/cxd2880_tnrdmd_dvbt_mon.c index fedc3b4a2fa0..86d5a1e4022a 100644 --- a/drivers/media/dvb-frontends/cxd2880/cxd2880_tnrdmd_dvbt_mon.c +++ b/drivers/media/dvb-frontends/cxd2880/cxd2880_tnrdmd_dvbt_mon.c @@ -11,7 +11,7 @@ #include "cxd2880_tnrdmd_dvbt.h" #include "cxd2880_tnrdmd_dvbt_mon.h" -#include +#include static const int ref_dbm_1000[3][5] = { {-93000, -91000, -90000, -89000, -88000}, diff --git a/drivers/media/dvb-frontends/cxd2880/cxd2880_top.c b/drivers/media/dvb-frontends/cxd2880/cxd2880_top.c index d5b1b3788e39..f67b6d24b8d4 100644 --- a/drivers/media/dvb-frontends/cxd2880/cxd2880_top.c +++ b/drivers/media/dvb-frontends/cxd2880/cxd2880_top.c @@ -11,7 +11,7 @@ #include #include -#include +#include #include "cxd2880.h" #include "cxd2880_tnrdmd_mon.h" diff --git a/drivers/media/dvb-frontends/dib7000p.c b/drivers/media/dvb-frontends/dib7000p.c index a90d2f51868f..b791e687d2e2 100644 --- a/drivers/media/dvb-frontends/dib7000p.c +++ b/drivers/media/dvb-frontends/dib7000p.c @@ -13,7 +13,7 @@ #include #include -#include +#include #include #include "dib7000p.h" diff --git a/drivers/media/dvb-frontends/dib8000.c b/drivers/media/dvb-frontends/dib8000.c index fe19d127abb3..2abda7d1cb6e 100644 --- a/drivers/media/dvb-frontends/dib8000.c +++ b/drivers/media/dvb-frontends/dib8000.c @@ -13,7 +13,7 @@ #include #include -#include +#include #include diff --git a/drivers/media/dvb-frontends/dib9000.c b/drivers/media/dvb-frontends/dib9000.c index 914ca820c174..1c57587a917a 100644 --- a/drivers/media/dvb-frontends/dib9000.c +++ b/drivers/media/dvb-frontends/dib9000.c @@ -11,7 +11,7 @@ #include #include -#include +#include #include #include "dib9000.h" diff --git a/drivers/media/dvb-frontends/drxk_hard.c b/drivers/media/dvb-frontends/drxk_hard.c index 3301ef75d441..6ad4f202f1bf 100644 --- a/drivers/media/dvb-frontends/drxk_hard.c +++ b/drivers/media/dvb-frontends/drxk_hard.c @@ -20,7 +20,7 @@ #include #include "drxk.h" #include "drxk_hard.h" -#include +#include static int power_down_dvbt(struct drxk_state *state, bool set_power_mode); static int power_down_qam(struct drxk_state *state); diff --git a/drivers/media/dvb-frontends/lgdt3305.c b/drivers/media/dvb-frontends/lgdt3305.c index 62d743988919..c15d3735d34c 100644 --- a/drivers/media/dvb-frontends/lgdt3305.c +++ b/drivers/media/dvb-frontends/lgdt3305.c @@ -10,7 +10,7 @@ #include #include #include -#include +#include #include "lgdt3305.h" static int debug; diff --git a/drivers/media/dvb-frontends/lgdt3306a.c b/drivers/media/dvb-frontends/lgdt3306a.c index 70258884126b..3c6650f6e9a3 100644 --- a/drivers/media/dvb-frontends/lgdt3306a.c +++ b/drivers/media/dvb-frontends/lgdt3306a.c @@ -12,7 +12,7 @@ #include #include #include -#include +#include #include "lgdt3306a.h" #include diff --git a/drivers/media/dvb-frontends/lgdt330x.c b/drivers/media/dvb-frontends/lgdt330x.c index 83565209c3b1..97a10996c7fa 100644 --- a/drivers/media/dvb-frontends/lgdt330x.c +++ b/drivers/media/dvb-frontends/lgdt330x.c @@ -28,7 +28,7 @@ #include #include -#include +#include #include "lgdt330x_priv.h" #include "lgdt330x.h" diff --git a/drivers/media/dvb-frontends/m88ds3103_priv.h b/drivers/media/dvb-frontends/m88ds3103_priv.h index aa5306f40201..594ad9cbc2cc 100644 --- a/drivers/media/dvb-frontends/m88ds3103_priv.h +++ b/drivers/media/dvb-frontends/m88ds3103_priv.h @@ -10,7 +10,7 @@ #include #include "m88ds3103.h" -#include +#include #include #include #include diff --git a/drivers/media/dvb-frontends/mn88443x.c b/drivers/media/dvb-frontends/mn88443x.c index 2ce5692bc22c..db2921c736af 100644 --- a/drivers/media/dvb-frontends/mn88443x.c +++ b/drivers/media/dvb-frontends/mn88443x.c @@ -10,7 +10,7 @@ #include #include #include -#include +#include #include "mn88443x.h" diff --git a/drivers/media/dvb-frontends/mn88472_priv.h b/drivers/media/dvb-frontends/mn88472_priv.h index 337562723f88..41f14bd67bfd 100644 --- a/drivers/media/dvb-frontends/mn88472_priv.h +++ b/drivers/media/dvb-frontends/mn88472_priv.h @@ -9,7 +9,7 @@ #define MN88472_PRIV_H #include -#include +#include #include "mn88472.h" #include #include diff --git a/drivers/media/dvb-frontends/mn88473_priv.h b/drivers/media/dvb-frontends/mn88473_priv.h index eca7f4e2b769..e9daaacfa22f 100644 --- a/drivers/media/dvb-frontends/mn88473_priv.h +++ b/drivers/media/dvb-frontends/mn88473_priv.h @@ -9,7 +9,7 @@ #define MN88473_PRIV_H #include -#include +#include #include "mn88473.h" #include #include diff --git a/drivers/media/dvb-frontends/or51132.c b/drivers/media/dvb-frontends/or51132.c index 24de1b115158..355f3598627b 100644 --- a/drivers/media/dvb-frontends/or51132.c +++ b/drivers/media/dvb-frontends/or51132.c @@ -27,7 +27,7 @@ #include #include -#include +#include #include #include "or51132.h" diff --git a/drivers/media/dvb-frontends/or51211.c b/drivers/media/dvb-frontends/or51211.c index ddcaea5c9941..ae732dc5116e 100644 --- a/drivers/media/dvb-frontends/or51211.c +++ b/drivers/media/dvb-frontends/or51211.c @@ -26,7 +26,7 @@ #include #include -#include +#include #include #include "or51211.h" diff --git a/drivers/media/dvb-frontends/rtl2830_priv.h b/drivers/media/dvb-frontends/rtl2830_priv.h index fae78ed78522..ae1fc24a4d84 100644 --- a/drivers/media/dvb-frontends/rtl2830_priv.h +++ b/drivers/media/dvb-frontends/rtl2830_priv.h @@ -9,7 +9,7 @@ #define RTL2830_PRIV_H #include -#include +#include #include "rtl2830.h" #include #include diff --git a/drivers/media/dvb-frontends/rtl2832_priv.h b/drivers/media/dvb-frontends/rtl2832_priv.h index 5f79f95b9475..f11ba038d5f0 100644 --- a/drivers/media/dvb-frontends/rtl2832_priv.h +++ b/drivers/media/dvb-frontends/rtl2832_priv.h @@ -14,7 +14,7 @@ #include #include -#include +#include #include "rtl2832.h" struct rtl2832_dev { diff --git a/drivers/media/dvb-frontends/si2165.c b/drivers/media/dvb-frontends/si2165.c index 72810efd1a96..434d003bf397 100644 --- a/drivers/media/dvb-frontends/si2165.c +++ b/drivers/media/dvb-frontends/si2165.c @@ -19,7 +19,7 @@ #include #include -#include +#include #include "si2165_priv.h" #include "si2165.h" diff --git a/drivers/media/dvb-frontends/stv0367.c b/drivers/media/dvb-frontends/stv0367.c index 95e376f23506..a93f40617469 100644 --- a/drivers/media/dvb-frontends/stv0367.c +++ b/drivers/media/dvb-frontends/stv0367.c @@ -15,7 +15,7 @@ #include #include -#include +#include #include "stv0367.h" #include "stv0367_defs.h" diff --git a/drivers/media/dvb-frontends/tc90522.c b/drivers/media/dvb-frontends/tc90522.c index 879f028f9682..1f8cbf45554a 100644 --- a/drivers/media/dvb-frontends/tc90522.c +++ b/drivers/media/dvb-frontends/tc90522.c @@ -21,7 +21,7 @@ #include #include #include -#include +#include #include "tc90522.h" #define TC90522_I2C_THRU_REG 0xfe diff --git a/drivers/media/dvb-frontends/tda10048.c b/drivers/media/dvb-frontends/tda10048.c index 0b3f6999515e..3cb4e5270e4f 100644 --- a/drivers/media/dvb-frontends/tda10048.c +++ b/drivers/media/dvb-frontends/tda10048.c @@ -16,7 +16,7 @@ #include #include #include -#include +#include #include "tda10048.h" #define TDA10048_DEFAULT_FIRMWARE "dvb-fe-tda10048-1.0.fw" diff --git a/include/media/dvb_math.h b/include/linux/int_log.h similarity index 63% rename from include/media/dvb_math.h rename to include/linux/int_log.h index 8690ec42954d..0a6f58c38b61 100644 --- a/include/media/dvb_math.h +++ b/include/linux/int_log.h @@ -1,22 +1,12 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ /* - * dvb-math provides some complex fixed-point math - * operations shared between the dvb related stuff + * Provides fixed-point logarithm operations. * * Copyright (C) 2006 Christoph Pfister (christophpfister@gmail.com) - * - * This library is free software; you can redistribute it and/or modify - * it under the terms of the GNU Lesser General Public License as - * published by the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details. */ -#ifndef __DVB_MATH_H -#define __DVB_MATH_H +#ifndef __LINUX_INT_LOG_H +#define __LINUX_INT_LOG_H #include diff --git a/lib/math/Makefile b/lib/math/Makefile index bfac26ddfc22..91fcdb0c9efe 100644 --- a/lib/math/Makefile +++ b/lib/math/Makefile @@ -1,5 +1,5 @@ # SPDX-License-Identifier: GPL-2.0-only -obj-y += div64.o gcd.o lcm.o int_pow.o int_sqrt.o reciprocal_div.o +obj-y += div64.o gcd.o lcm.o int_log.o int_pow.o int_sqrt.o reciprocal_div.o obj-$(CONFIG_CORDIC) += cordic.o obj-$(CONFIG_PRIME_NUMBERS) += prime_numbers.o diff --git a/drivers/media/dvb-core/dvb_math.c b/lib/math/int_log.c similarity index 84% rename from drivers/media/dvb-core/dvb_math.c rename to lib/math/int_log.c index dc90564d7f34..8f9da3a2ad39 100644 --- a/drivers/media/dvb-core/dvb_math.c +++ b/lib/math/int_log.c @@ -1,25 +1,17 @@ +// SPDX-License-Identifier: LGPL-2.1-or-later /* - * dvb-math provides some complex fixed-point math - * operations shared between the dvb related stuff + * Provides fixed-point logarithm operations. * * Copyright (C) 2006 Christoph Pfister (christophpfister@gmail.com) - * - * This library is free software; you can redistribute it and/or modify - * it under the terms of the GNU Lesser General Public License as - * published by the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details. */ #include +#include +#include #include -#include +#include + #include -#include static const unsigned short logtable[256] = { 0x0000, 0x0171, 0x02e0, 0x044e, 0x05ba, 0x0725, 0x088e, 0x09f7, @@ -53,7 +45,7 @@ static const unsigned short logtable[256] = { 0xe82a, 0xe8ef, 0xe9b3, 0xea77, 0xeb3b, 0xebfe, 0xecc1, 0xed83, 0xee45, 0xef06, 0xefc8, 0xf088, 0xf149, 0xf209, 0xf2c8, 0xf387, 0xf446, 0xf505, 0xf5c3, 0xf680, 0xf73e, 0xf7fb, 0xf8b7, 0xf973, - 0xfa2f, 0xfaea, 0xfba5, 0xfc60, 0xfd1a, 0xfdd4, 0xfe8e, 0xff47 + 0xfa2f, 0xfaea, 0xfba5, 0xfc60, 0xfd1a, 0xfdd4, 0xfe8e, 0xff47, }; unsigned int intlog2(u32 value) @@ -90,7 +82,7 @@ unsigned int intlog2(u32 value) * so we would use the entry 0x18 */ significand = value << (31 - msb); - logentry = (significand >> 23) & 0xff; + logentry = (significand >> 23) % ARRAY_SIZE(logtable); /** * last step we do is interpolation because of the @@ -108,7 +100,7 @@ unsigned int intlog2(u32 value) * logtable_next is 256 */ interpolation = ((significand & 0x7fffff) * - ((logtable[(logentry + 1) & 0xff] - + ((logtable[(logentry + 1) % ARRAY_SIZE(logtable)] - logtable[logentry]) & 0xffff)) >> 15; /* now we return the result */ diff --git a/sound/soc/codecs/nau8825.c b/sound/soc/codecs/nau8825.c index 9e0e4ddf128e..5cb0de648bd3 100644 --- a/sound/soc/codecs/nau8825.c +++ b/sound/soc/codecs/nau8825.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -38,7 +39,6 @@ #define NAU_FVCO_MIN 90000000 /* cross talk suppression detection */ -#define LOG10_MAGIC 646456993 #define GAIN_AUGMENT 22500 #define SIDETONE_BASE 207000 @@ -219,42 +219,6 @@ static const struct reg_sequence nau8825_regmap_patch[] = { { NAU8825_REG_MIC_BIAS, 0x0046 }, }; - -static const unsigned short logtable[256] = { - 0x0000, 0x0171, 0x02e0, 0x044e, 0x05ba, 0x0725, 0x088e, 0x09f7, - 0x0b5d, 0x0cc3, 0x0e27, 0x0f8a, 0x10eb, 0x124b, 0x13aa, 0x1508, - 0x1664, 0x17bf, 0x1919, 0x1a71, 0x1bc8, 0x1d1e, 0x1e73, 0x1fc6, - 0x2119, 0x226a, 0x23ba, 0x2508, 0x2656, 0x27a2, 0x28ed, 0x2a37, - 0x2b80, 0x2cc8, 0x2e0f, 0x2f54, 0x3098, 0x31dc, 0x331e, 0x345f, - 0x359f, 0x36de, 0x381b, 0x3958, 0x3a94, 0x3bce, 0x3d08, 0x3e41, - 0x3f78, 0x40af, 0x41e4, 0x4319, 0x444c, 0x457f, 0x46b0, 0x47e1, - 0x4910, 0x4a3f, 0x4b6c, 0x4c99, 0x4dc5, 0x4eef, 0x5019, 0x5142, - 0x526a, 0x5391, 0x54b7, 0x55dc, 0x5700, 0x5824, 0x5946, 0x5a68, - 0x5b89, 0x5ca8, 0x5dc7, 0x5ee5, 0x6003, 0x611f, 0x623a, 0x6355, - 0x646f, 0x6588, 0x66a0, 0x67b7, 0x68ce, 0x69e4, 0x6af8, 0x6c0c, - 0x6d20, 0x6e32, 0x6f44, 0x7055, 0x7165, 0x7274, 0x7383, 0x7490, - 0x759d, 0x76aa, 0x77b5, 0x78c0, 0x79ca, 0x7ad3, 0x7bdb, 0x7ce3, - 0x7dea, 0x7ef0, 0x7ff6, 0x80fb, 0x81ff, 0x8302, 0x8405, 0x8507, - 0x8608, 0x8709, 0x8809, 0x8908, 0x8a06, 0x8b04, 0x8c01, 0x8cfe, - 0x8dfa, 0x8ef5, 0x8fef, 0x90e9, 0x91e2, 0x92db, 0x93d2, 0x94ca, - 0x95c0, 0x96b6, 0x97ab, 0x98a0, 0x9994, 0x9a87, 0x9b7a, 0x9c6c, - 0x9d5e, 0x9e4f, 0x9f3f, 0xa02e, 0xa11e, 0xa20c, 0xa2fa, 0xa3e7, - 0xa4d4, 0xa5c0, 0xa6ab, 0xa796, 0xa881, 0xa96a, 0xaa53, 0xab3c, - 0xac24, 0xad0c, 0xadf2, 0xaed9, 0xafbe, 0xb0a4, 0xb188, 0xb26c, - 0xb350, 0xb433, 0xb515, 0xb5f7, 0xb6d9, 0xb7ba, 0xb89a, 0xb97a, - 0xba59, 0xbb38, 0xbc16, 0xbcf4, 0xbdd1, 0xbead, 0xbf8a, 0xc065, - 0xc140, 0xc21b, 0xc2f5, 0xc3cf, 0xc4a8, 0xc580, 0xc658, 0xc730, - 0xc807, 0xc8de, 0xc9b4, 0xca8a, 0xcb5f, 0xcc34, 0xcd08, 0xcddc, - 0xceaf, 0xcf82, 0xd054, 0xd126, 0xd1f7, 0xd2c8, 0xd399, 0xd469, - 0xd538, 0xd607, 0xd6d6, 0xd7a4, 0xd872, 0xd93f, 0xda0c, 0xdad9, - 0xdba5, 0xdc70, 0xdd3b, 0xde06, 0xded0, 0xdf9a, 0xe063, 0xe12c, - 0xe1f5, 0xe2bd, 0xe385, 0xe44c, 0xe513, 0xe5d9, 0xe69f, 0xe765, - 0xe82a, 0xe8ef, 0xe9b3, 0xea77, 0xeb3b, 0xebfe, 0xecc1, 0xed83, - 0xee45, 0xef06, 0xefc8, 0xf088, 0xf149, 0xf209, 0xf2c8, 0xf387, - 0xf446, 0xf505, 0xf5c3, 0xf680, 0xf73e, 0xf7fb, 0xf8b7, 0xf973, - 0xfa2f, 0xfaea, 0xfba5, 0xfc60, 0xfd1a, 0xfdd4, 0xfe8e, 0xff47 -}; - /** * nau8825_sema_acquire - acquire the semaphore of nau88l25 * @nau8825: component to register the codec private data with @@ -368,65 +332,14 @@ static void nau8825_hpvol_ramp(struct nau8825 *nau8825, } /** - * nau8825_intlog10_dec3 - Computes log10 of a value - * the result is round off to 3 decimal. This function takes reference to - * dvb-math. The source code locates as the following. - * Linux/drivers/media/dvb-core/dvb_math.c + * nau8825_intlog10_dec3 - Computes log10 of a value, rounding the result to 3 decimal places. * @value: input for log10 * * return log10(value) * 1000 */ static u32 nau8825_intlog10_dec3(u32 value) { - u32 msb, logentry, significand, interpolation, log10val; - u64 log2val; - - /* first detect the msb (count begins at 0) */ - msb = fls(value) - 1; - /** - * now we use a logtable after the following method: - * - * log2(2^x * y) * 2^24 = x * 2^24 + log2(y) * 2^24 - * where x = msb and therefore 1 <= y < 2 - * first y is determined by shifting the value left - * so that msb is bit 31 - * 0x00231f56 -> 0x8C7D5800 - * the result is y * 2^31 -> "significand" - * then the highest 9 bits are used for a table lookup - * the highest bit is discarded because it's always set - * the highest nine bits in our example are 100011000 - * so we would use the entry 0x18 - */ - significand = value << (31 - msb); - logentry = (significand >> 23) & 0xff; - /** - * last step we do is interpolation because of the - * limitations of the log table the error is that part of - * the significand which isn't used for lookup then we - * compute the ratio between the error and the next table entry - * and interpolate it between the log table entry used and the - * next one the biggest error possible is 0x7fffff - * (in our example it's 0x7D5800) - * needed value for next table entry is 0x800000 - * so the interpolation is - * (error / 0x800000) * (logtable_next - logtable_current) - * in the implementation the division is moved to the end for - * better accuracy there is also an overflow correction if - * logtable_next is 256 - */ - interpolation = ((significand & 0x7fffff) * - ((logtable[(logentry + 1) & 0xff] - - logtable[logentry]) & 0xffff)) >> 15; - - log2val = ((msb << 24) + (logtable[logentry] << 8) + interpolation); - /** - * log10(x) = log2(x) * log10(2) - */ - log10val = (log2val * LOG10_MAGIC) >> 31; - /** - * the result is round off to 3 decimal - */ - return log10val / ((1 << 24) / 1000); + return intlog10(value) / ((1 << 24) / 1000); } /**