/* * Clutter. * * An OpenGL based 'interactive canvas' library. * * Authored By Matthew Allum * * Copyright (C) 2006 OpenedHand * * 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 of the License, or (at your option) any later version. * * This library 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. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the * Free Software Foundation, Inc., 59 Temple Place - Suite 330, * Boston, MA 02111-1307, USA. */ #include /* pre-computed sin table for 1st quadrant * * Currently contains 257 entries. * * The current error (compared to system sin) is about * 0.5% for values near the start of the table where the * curve is steep, but improving rapidly. If this precission * is not enough, we can increase the size of the table */ static ClutterFixed sin_tbl [] = { 0x00000000L, 0x00000192L, 0x00000324L, 0x000004B6L, 0x00000648L, 0x000007DAL, 0x0000096CL, 0x00000AFEL, 0x00000C90L, 0x00000E21L, 0x00000FB3L, 0x00001144L, 0x000012D5L, 0x00001466L, 0x000015F7L, 0x00001787L, 0x00001918L, 0x00001AA8L, 0x00001C38L, 0x00001DC7L, 0x00001F56L, 0x000020E5L, 0x00002274L, 0x00002402L, 0x00002590L, 0x0000271EL, 0x000028ABL, 0x00002A38L, 0x00002BC4L, 0x00002D50L, 0x00002EDCL, 0x00003067L, 0x000031F1L, 0x0000337CL, 0x00003505L, 0x0000368EL, 0x00003817L, 0x0000399FL, 0x00003B27L, 0x00003CAEL, 0x00003E34L, 0x00003FBAL, 0x0000413FL, 0x000042C3L, 0x00004447L, 0x000045CBL, 0x0000474DL, 0x000048CFL, 0x00004A50L, 0x00004BD1L, 0x00004D50L, 0x00004ECFL, 0x0000504DL, 0x000051CBL, 0x00005348L, 0x000054C3L, 0x0000563EL, 0x000057B9L, 0x00005932L, 0x00005AAAL, 0x00005C22L, 0x00005D99L, 0x00005F0FL, 0x00006084L, 0x000061F8L, 0x0000636BL, 0x000064DDL, 0x0000664EL, 0x000067BEL, 0x0000692DL, 0x00006A9BL, 0x00006C08L, 0x00006D74L, 0x00006EDFL, 0x00007049L, 0x000071B2L, 0x0000731AL, 0x00007480L, 0x000075E6L, 0x0000774AL, 0x000078ADL, 0x00007A10L, 0x00007B70L, 0x00007CD0L, 0x00007E2FL, 0x00007F8CL, 0x000080E8L, 0x00008243L, 0x0000839CL, 0x000084F5L, 0x0000864CL, 0x000087A1L, 0x000088F6L, 0x00008A49L, 0x00008B9AL, 0x00008CEBL, 0x00008E3AL, 0x00008F88L, 0x000090D4L, 0x0000921FL, 0x00009368L, 0x000094B0L, 0x000095F7L, 0x0000973CL, 0x00009880L, 0x000099C2L, 0x00009B03L, 0x00009C42L, 0x00009D80L, 0x00009EBCL, 0x00009FF7L, 0x0000A130L, 0x0000A268L, 0x0000A39EL, 0x0000A4D2L, 0x0000A605L, 0x0000A736L, 0x0000A866L, 0x0000A994L, 0x0000AAC1L, 0x0000ABEBL, 0x0000AD14L, 0x0000AE3CL, 0x0000AF62L, 0x0000B086L, 0x0000B1A8L, 0x0000B2C9L, 0x0000B3E8L, 0x0000B505L, 0x0000B620L, 0x0000B73AL, 0x0000B852L, 0x0000B968L, 0x0000BA7DL, 0x0000BB8FL, 0x0000BCA0L, 0x0000BDAFL, 0x0000BEBCL, 0x0000BFC7L, 0x0000C0D1L, 0x0000C1D8L, 0x0000C2DEL, 0x0000C3E2L, 0x0000C4E4L, 0x0000C5E4L, 0x0000C6E2L, 0x0000C7DEL, 0x0000C8D9L, 0x0000C9D1L, 0x0000CAC7L, 0x0000CBBCL, 0x0000CCAEL, 0x0000CD9FL, 0x0000CE8EL, 0x0000CF7AL, 0x0000D065L, 0x0000D14DL, 0x0000D234L, 0x0000D318L, 0x0000D3FBL, 0x0000D4DBL, 0x0000D5BAL, 0x0000D696L, 0x0000D770L, 0x0000D848L, 0x0000D91EL, 0x0000D9F2L, 0x0000DAC4L, 0x0000DB94L, 0x0000DC62L, 0x0000DD2DL, 0x0000DDF7L, 0x0000DEBEL, 0x0000DF83L, 0x0000E046L, 0x0000E107L, 0x0000E1C6L, 0x0000E282L, 0x0000E33CL, 0x0000E3F4L, 0x0000E4AAL, 0x0000E55EL, 0x0000E610L, 0x0000E6BFL, 0x0000E76CL, 0x0000E817L, 0x0000E8BFL, 0x0000E966L, 0x0000EA0AL, 0x0000EAABL, 0x0000EB4BL, 0x0000EBE8L, 0x0000EC83L, 0x0000ED1CL, 0x0000EDB3L, 0x0000EE47L, 0x0000EED9L, 0x0000EF68L, 0x0000EFF5L, 0x0000F080L, 0x0000F109L, 0x0000F18FL, 0x0000F213L, 0x0000F295L, 0x0000F314L, 0x0000F391L, 0x0000F40CL, 0x0000F484L, 0x0000F4FAL, 0x0000F56EL, 0x0000F5DFL, 0x0000F64EL, 0x0000F6BAL, 0x0000F724L, 0x0000F78CL, 0x0000F7F1L, 0x0000F854L, 0x0000F8B4L, 0x0000F913L, 0x0000F96EL, 0x0000F9C8L, 0x0000FA1FL, 0x0000FA73L, 0x0000FAC5L, 0x0000FB15L, 0x0000FB62L, 0x0000FBADL, 0x0000FBF5L, 0x0000FC3BL, 0x0000FC7FL, 0x0000FCC0L, 0x0000FCFEL, 0x0000FD3BL, 0x0000FD74L, 0x0000FDACL, 0x0000FDE1L, 0x0000FE13L, 0x0000FE43L, 0x0000FE71L, 0x0000FE9CL, 0x0000FEC4L, 0x0000FEEBL, 0x0000FF0EL, 0x0000FF30L, 0x0000FF4EL, 0x0000FF6BL, 0x0000FF85L, 0x0000FF9CL, 0x0000FFB1L, 0x0000FFC4L, 0x0000FFD4L, 0x0000FFE1L, 0x0000FFECL, 0x0000FFF5L, 0x0000FFFBL, 0x0000FFFFL, 0x00010000L, }; /* the difference of the angle for two adjacent values in the table * expressed as ClutterFixed number */ #define CFX_SIN_STEP 0x00000192 /** * clutter_sinx: * @angle: a #ClutterFixed angle in radians * * Fixed point implementation of sine function * * Return value: #ClutterFixed sine value. * * Since: 0.2 */ ClutterFixed clutter_sinx (ClutterFixed angle) { int sign = 1, indx1, indx2; ClutterFixed low, high, d1, d2; /* convert negative angle to positive + sign */ if ((int)angle < 0) { sign = 1 + ~sign; angle = 1 + ~angle; } /* reduce to <0, 2*pi) */ if (angle >= CFX_2PI) { ClutterFixed f = CLUTTER_FIXED_DIV (angle, CFX_2PI); angle = angle - f; } /* reduce to first quadrant and sign */ if (angle > CFX_PI) { sign = 1 + ~sign; if (angle > CFX_PI + CFX_PI_2) { /* fourth qudrant */ angle = CFX_2PI - angle; } else { /* third quadrant */ angle -= CFX_PI; } } else { if (angle > CFX_PI_2) { /* second quadrant */ angle = CFX_PI - angle; } } /* Calculate indices of the two nearest values in our table * and return weighted average * * Handle the end of the table gracefully */ indx1 = CLUTTER_FIXED_DIV (angle, CFX_SIN_STEP); indx1 = CLUTTER_FIXED_INT (indx1); if (indx1 == sizeof (sin_tbl)/sizeof (ClutterFixed) - 1) { indx2 = indx1; indx1 = indx2 - 1; } else { indx2 = indx1 + 1; } low = sin_tbl[indx1]; high = sin_tbl[indx2]; d1 = angle - indx1 * CFX_SIN_STEP; d2 = indx2 * CFX_SIN_STEP - angle; angle = ((low * d2 + high * d1) / (CFX_SIN_STEP)); if (sign < 0) angle = (1 + ~angle); return angle; } /** * clutter_sini: * @angle: a #ClutterAngle * * Very fast fixed point implementation of sine function. * * ClutterAngle is an integer such that 1024 represents * full circle. * * Return value: #ClutterFixed sine value. * * Since: 0.2 */ ClutterFixed clutter_sini (ClutterAngle angle) { int sign = 1; ClutterFixed result; /* reduce negative angle to positive + sign */ if (angle < 0) { sign = 1 + ~sign; angle = 1 + ~angle; } /* reduce to <0, 2*pi) */ angle &= 0x7ff; /* reduce to first quadrant and sign */ if (angle > 512) { sign = 1 + ~sign; if (angle > 768) { /* fourth qudrant */ angle = 1024 - angle; } else { /* third quadrant */ angle -= 512; } } else { if (angle > 256) { /* second quadrant */ angle = 512 - angle; } } result = sin_tbl[angle]; if (sign < 0) result = (1 + ~result); return result; } /* pre-computed tan table for 1st quadrant * * Currently contains 257 entries. * */ static ClutterFixed tan_tbl [] = { 0x00000000L, 0x00000192L, 0x00000324L, 0x000004b7L, 0x00000649L, 0x000007dbL, 0x0000096eL, 0x00000b01L, 0x00000c94L, 0x00000e27L, 0x00000fbaL, 0x0000114eL, 0x000012e2L, 0x00001477L, 0x0000160cL, 0x000017a1L, 0x00001937L, 0x00001acdL, 0x00001c64L, 0x00001dfbL, 0x00001f93L, 0x0000212cL, 0x000022c5L, 0x0000245fL, 0x000025f9L, 0x00002795L, 0x00002931L, 0x00002aceL, 0x00002c6cL, 0x00002e0aL, 0x00002faaL, 0x0000314aL, 0x000032ecL, 0x0000348eL, 0x00003632L, 0x000037d7L, 0x0000397dL, 0x00003b24L, 0x00003cccL, 0x00003e75L, 0x00004020L, 0x000041ccL, 0x00004379L, 0x00004528L, 0x000046d8L, 0x0000488aL, 0x00004a3dL, 0x00004bf2L, 0x00004da8L, 0x00004f60L, 0x0000511aL, 0x000052d5L, 0x00005492L, 0x00005651L, 0x00005812L, 0x000059d5L, 0x00005b99L, 0x00005d60L, 0x00005f28L, 0x000060f3L, 0x000062c0L, 0x0000648fL, 0x00006660L, 0x00006834L, 0x00006a0aL, 0x00006be2L, 0x00006dbdL, 0x00006f9aL, 0x0000717aL, 0x0000735dL, 0x00007542L, 0x0000772aL, 0x00007914L, 0x00007b02L, 0x00007cf2L, 0x00007ee6L, 0x000080dcL, 0x000082d6L, 0x000084d2L, 0x000086d2L, 0x000088d6L, 0x00008adcL, 0x00008ce7L, 0x00008ef4L, 0x00009106L, 0x0000931bL, 0x00009534L, 0x00009750L, 0x00009971L, 0x00009b95L, 0x00009dbeL, 0x00009febL, 0x0000a21cL, 0x0000a452L, 0x0000a68cL, 0x0000a8caL, 0x0000ab0eL, 0x0000ad56L, 0x0000afa3L, 0x0000b1f5L, 0x0000b44cL, 0x0000b6a8L, 0x0000b909L, 0x0000bb70L, 0x0000bdddL, 0x0000c04fL, 0x0000c2c7L, 0x0000c545L, 0x0000c7c9L, 0x0000ca53L, 0x0000cce3L, 0x0000cf7aL, 0x0000d218L, 0x0000d4bcL, 0x0000d768L, 0x0000da1aL, 0x0000dcd4L, 0x0000df95L, 0x0000e25eL, 0x0000e52eL, 0x0000e806L, 0x0000eae7L, 0x0000edd0L, 0x0000f0c1L, 0x0000f3bbL, 0x0000f6bfL, 0x0000f9cbL, 0x0000fce1L, 0x00010000L, 0x00010329L, 0x0001065dL, 0x0001099aL, 0x00010ce3L, 0x00011036L, 0x00011394L, 0x000116feL, 0x00011a74L, 0x00011df6L, 0x00012184L, 0x0001251fL, 0x000128c6L, 0x00012c7cL, 0x0001303fL, 0x00013410L, 0x000137f0L, 0x00013bdfL, 0x00013fddL, 0x000143ebL, 0x00014809L, 0x00014c37L, 0x00015077L, 0x000154c9L, 0x0001592dL, 0x00015da4L, 0x0001622eL, 0x000166ccL, 0x00016b7eL, 0x00017045L, 0x00017523L, 0x00017a17L, 0x00017f22L, 0x00018444L, 0x00018980L, 0x00018ed5L, 0x00019445L, 0x000199cfL, 0x00019f76L, 0x0001a53aL, 0x0001ab1cL, 0x0001b11dL, 0x0001b73fL, 0x0001bd82L, 0x0001c3e7L, 0x0001ca71L, 0x0001d11fL, 0x0001d7f4L, 0x0001def1L, 0x0001e618L, 0x0001ed6aL, 0x0001f4e8L, 0x0001fc96L, 0x00020473L, 0x00020c84L, 0x000214c9L, 0x00021d44L, 0x000225f9L, 0x00022ee9L, 0x00023818L, 0x00024187L, 0x00024b3aL, 0x00025534L, 0x00025f78L, 0x00026a0aL, 0x000274edL, 0x00028026L, 0x00028bb8L, 0x000297a8L, 0x0002a3fbL, 0x0002b0b5L, 0x0002bdddL, 0x0002cb79L, 0x0002d98eL, 0x0002e823L, 0x0002f740L, 0x000306ecL, 0x00031730L, 0x00032816L, 0x000339a6L, 0x00034bebL, 0x00035ef2L, 0x000372c6L, 0x00038776L, 0x00039d11L, 0x0003b3a6L, 0x0003cb48L, 0x0003e40aL, 0x0003fe02L, 0x00041949L, 0x000435f7L, 0x0004542bL, 0x00047405L, 0x000495a9L, 0x0004b940L, 0x0004def6L, 0x00050700L, 0x00053196L, 0x00055ef9L, 0x00058f75L, 0x0005c35dL, 0x0005fb14L, 0x00063709L, 0x000677c0L, 0x0006bdd0L, 0x000709ecL, 0x00075ce6L, 0x0007b7bbL, 0x00081b98L, 0x000889e9L, 0x0009046eL, 0x00098d4dL, 0x000a2736L, 0x000ad593L, 0x000b9cc6L, 0x000c828aL, 0x000d8e82L, 0x000ecb1bL, 0x001046eaL, 0x00121703L, 0x00145b00L, 0x0017448dL, 0x001b2672L, 0x002095afL, 0x0028bc49L, 0x0036519aL, 0x00517bb6L, 0x00a2f8fdL, 0x46d3eab2L, }; /** * clutter_tani: * @angle: a #ClutterAngle * * Very fast fixed point implementation of tan function. * * ClutterAngle is an integer such that 1024 represents * full circle. * * Return value: #ClutterFixed sine value. * * Since: 0.3 */ ClutterFixed clutter_tani (ClutterAngle angle) { int sign = 1; ClutterFixed result; /* reduce negative angle to positive + sign */ if (angle < 0) { sign = 1 + ~sign; angle = 1 + ~angle; } /* reduce to <0, pi) */ angle &= 0x1ff; /* reduce to first quadrant and sign */ if (angle > 256) { sign = 1 + ~sign; angle = 512 - angle; } result = tan_tbl[angle]; if (sign < 0) result = (1 + ~result); return result; } ClutterFixed sqrt_tbl [] = { 0x00000000L, 0x00010000L, 0x00016A0AL, 0x0001BB68L, 0x00020000L, 0x00023C6FL, 0x00027312L, 0x0002A550L, 0x0002D414L, 0x00030000L, 0x0003298BL, 0x0003510EL, 0x000376CFL, 0x00039B05L, 0x0003BDDDL, 0x0003DF7CL, 0x00040000L, 0x00041F84L, 0x00043E1EL, 0x00045BE1L, 0x000478DEL, 0x00049524L, 0x0004B0BFL, 0x0004CBBCL, 0x0004E624L, 0x00050000L, 0x00051959L, 0x00053237L, 0x00054AA0L, 0x0005629AL, 0x00057A2BL, 0x00059159L, 0x0005A828L, 0x0005BE9CL, 0x0005D4B9L, 0x0005EA84L, 0x00060000L, 0x00061530L, 0x00062A17L, 0x00063EB8L, 0x00065316L, 0x00066733L, 0x00067B12L, 0x00068EB4L, 0x0006A21DL, 0x0006B54DL, 0x0006C847L, 0x0006DB0CL, 0x0006ED9FL, 0x00070000L, 0x00071232L, 0x00072435L, 0x0007360BL, 0x000747B5L, 0x00075935L, 0x00076A8CL, 0x00077BBBL, 0x00078CC2L, 0x00079DA3L, 0x0007AE60L, 0x0007BEF8L, 0x0007CF6DL, 0x0007DFBFL, 0x0007EFF0L, 0x00080000L, 0x00080FF0L, 0x00081FC1L, 0x00082F73L, 0x00083F08L, 0x00084E7FL, 0x00085DDAL, 0x00086D18L, 0x00087C3BL, 0x00088B44L, 0x00089A32L, 0x0008A906L, 0x0008B7C2L, 0x0008C664L, 0x0008D4EEL, 0x0008E361L, 0x0008F1BCL, 0x00090000L, 0x00090E2EL, 0x00091C45L, 0x00092A47L, 0x00093834L, 0x0009460CL, 0x000953CFL, 0x0009617EL, 0x00096F19L, 0x00097CA1L, 0x00098A16L, 0x00099777L, 0x0009A4C6L, 0x0009B203L, 0x0009BF2EL, 0x0009CC47L, 0x0009D94FL, 0x0009E645L, 0x0009F32BL, 0x000A0000L, 0x000A0CC5L, 0x000A1979L, 0x000A261EL, 0x000A32B3L, 0x000A3F38L, 0x000A4BAEL, 0x000A5816L, 0x000A646EL, 0x000A70B8L, 0x000A7CF3L, 0x000A8921L, 0x000A9540L, 0x000AA151L, 0x000AAD55L, 0x000AB94BL, 0x000AC534L, 0x000AD110L, 0x000ADCDFL, 0x000AE8A1L, 0x000AF457L, 0x000B0000L, 0x000B0B9DL, 0x000B172DL, 0x000B22B2L, 0x000B2E2BL, 0x000B3998L, 0x000B44F9L, 0x000B504FL, 0x000B5B9AL, 0x000B66D9L, 0x000B720EL, 0x000B7D37L, 0x000B8856L, 0x000B936AL, 0x000B9E74L, 0x000BA973L, 0x000BB467L, 0x000BBF52L, 0x000BCA32L, 0x000BD508L, 0x000BDFD5L, 0x000BEA98L, 0x000BF551L, 0x000C0000L, 0x000C0AA6L, 0x000C1543L, 0x000C1FD6L, 0x000C2A60L, 0x000C34E1L, 0x000C3F59L, 0x000C49C8L, 0x000C542EL, 0x000C5E8CL, 0x000C68E0L, 0x000C732DL, 0x000C7D70L, 0x000C87ACL, 0x000C91DFL, 0x000C9C0AL, 0x000CA62CL, 0x000CB047L, 0x000CBA59L, 0x000CC464L, 0x000CCE66L, 0x000CD861L, 0x000CE254L, 0x000CEC40L, 0x000CF624L, 0x000D0000L, 0x000D09D5L, 0x000D13A2L, 0x000D1D69L, 0x000D2727L, 0x000D30DFL, 0x000D3A90L, 0x000D4439L, 0x000D4DDCL, 0x000D5777L, 0x000D610CL, 0x000D6A9AL, 0x000D7421L, 0x000D7DA1L, 0x000D871BL, 0x000D908EL, 0x000D99FAL, 0x000DA360L, 0x000DACBFL, 0x000DB618L, 0x000DBF6BL, 0x000DC8B7L, 0x000DD1FEL, 0x000DDB3DL, 0x000DE477L, 0x000DEDABL, 0x000DF6D8L, 0x000E0000L, 0x000E0922L, 0x000E123DL, 0x000E1B53L, 0x000E2463L, 0x000E2D6DL, 0x000E3672L, 0x000E3F70L, 0x000E4869L, 0x000E515DL, 0x000E5A4BL, 0x000E6333L, 0x000E6C16L, 0x000E74F3L, 0x000E7DCBL, 0x000E869DL, 0x000E8F6BL, 0x000E9832L, 0x000EA0F5L, 0x000EA9B2L, 0x000EB26BL, 0x000EBB1EL, 0x000EC3CBL, 0x000ECC74L, 0x000ED518L, 0x000EDDB7L, 0x000EE650L, 0x000EEEE5L, 0x000EF775L, 0x000F0000L, 0x000F0886L, 0x000F1107L, 0x000F1984L, 0x000F21FCL, 0x000F2A6FL, 0x000F32DDL, 0x000F3B47L, 0x000F43ACL, 0x000F4C0CL, 0x000F5468L, 0x000F5CBFL, 0x000F6512L, 0x000F6D60L, 0x000F75AAL, 0x000F7DEFL, 0x000F8630L, 0x000F8E6DL, 0x000F96A5L, 0x000F9ED9L, 0x000FA709L, 0x000FAF34L, 0x000FB75BL, 0x000FBF7EL, 0x000FC79DL, 0x000FCFB7L, 0x000FD7CEL, 0x000FDFE0L, 0x000FE7EEL, 0x000FEFF8L, 0x000FF7FEL, 0x00100000L, }; /** * clutter_sqrtx: * @x: a #ClutterFixed * * A fixed point implementation of squre root * * Return value: #ClutterFixed square root. * * Since: 0.2 */ ClutterFixed clutter_sqrtx (ClutterFixed x) { /* The idea for this comes from the Alegro library, exploiting the * fact that, * sqrt (x) = sqrt (x/d) * sqrt (d); * * For d == 2^(n): * * sqrt (x) = sqrt (x/2^(2n)) * 2^n * * By locating suitable n for given x such that x >> 2n is in <0,255> * we can use a LUT of precomputed values. * * This algorithm provides both good performance and precission; * on ARM this function is about 5 times faster than c-lib sqrt, whilst * producing errors < 1%. * */ int t = 0; int sh = 0; unsigned int mask = 0x40000000; unsigned fract = x & 0x0000ffff; unsigned int d1, d2; if (x <= 0) return 0; if (x > CFX_255 || x < CFX_ONE) { /* * Find the highest bit set */ #if __arm__ /* This actually requires at least arm v5, but gcc does not seem * to set the architecture defines correctly, and it is I think * very unlikely that anyone will want to use clutter on anything * less than v5. */ int bit; __asm__ ("clz %0, %1\n" "rsb %0, %0, #31\n" :"=r"(bit) :"r" (x)); /* make even (2n) */ bit &= 0xfffffffe; #else /* TODO -- add i386 branch using bshr */ int bit = 30; while (bit >= 0) { if (x & mask) break; mask = (mask >> 1 | mask >> 2); bit -= 2; } #endif /* now bit indicates the highest bit set; there are two scenarios * * 1) bit < 23: Our number is smaller so we shift it left to maximase * precision (< 16 really, since <16,23> never goes * through here. * * 2) bit > 23: our number is above the table, so we shift right */ sh = ((bit - 22) >> 1); if (bit >= 8) t = (x >> (16 - 22 + bit)); else t = (x << (22 - 16 - bit)); } else { t = CLUTTER_FIXED_INT (x); } /* Do a weighted average of the two nearest values */ ClutterFixed v1 = sqrt_tbl[t]; ClutterFixed v2 = sqrt_tbl[t+1]; /* * 12 is fairly arbitrary -- we want integer that is not too big to cost * us precission */ d1 = (unsigned)(fract) >> 12; d2 = ((unsigned)CFX_ONE >> 12) - d1; x = ((v1*d2) + (v2*d1))/(CFX_ONE >> 12); if (sh > 0) x = x << sh; else if (sh < 0) x = (x >> (1 + ~sh)); return x; } /** * clutter_sqrti: * @x: integer value * * Very fast fixed point implementation of square root for integers. * * This function is about 10x faster than clib sqrt() on x86, and (this is * not a typo!) more than 800x faster on ARM without FPU. It's error is < 5% * for arguments < 132 and < 10% for arguments < 5591. * * Return value: integer square root. * * * Since: 0.2 */ gint clutter_sqrti (gint number) { /* This is a fixed point implementation of the Quake III sqrt algorithm, * described, for example, at * http://www.codemaestro.com/reviews/review00000105.html * * While the original QIII is extremely fast, the use of floating division * and multiplication makes it perform very on arm processors without FPU. * * The key to successfully replacing the floating point operations with * fixed point is in the choice of the fixed point format. The QIII * algorithm does not calculate the square root, but its reciprocal ('y' * below), which is only at the end turned to the inverse value. In order * for the algorithm to produce satisfactory results, the reciprocal value * must be represented with sufficient precission; the 16.16 we use * elsewhere in clutter is not good enough, and 10.22 is used instead. */ ClutterFixed x; unsigned long y1; /* 10.22 fixed point */ unsigned long f = 0x600000; /* '1.5' as 10.22 fixed */ union { float f; unsigned long i; } flt, flt2; flt.f = number; x = CLUTTER_INT_TO_FIXED (number) / 2; /* The QIII initial estimate */ flt.i = 0x5f3759df - ( flt.i >> 1 ); /* Now, we convert the float to 10.22 fixed. We exploit the mechanism * described at http://www.d6.com/users/checker/pdfs/gdmfp.pdf. * * We want 22 bit fraction; a single precission float uses 23 bit * mantisa, so we only need to add 2^(23-22) (no need for the 1.5 * multiplier as we are only dealing with positive numbers). * * Note: we have to use two separate variables here -- for some reason, * if we try to use just the flt variable, gcc on ARM optimises the whole * addition out, and it all goes pear shape, since without it, the bits * in the float will not be correctly aligned. */ flt2.f = flt.f + 2.0; flt2.i &= 0x7FFFFF; /* Now we correct the estimate, only single iterration is needed */ y1 = (flt2.i >> 11) * (flt2.i >> 11); y1 = (y1 >> 8) * (x >> 8); y1 = f - y1; flt2.i = (flt2.i >> 11) * (y1 >> 11); /* Invert, round and convert from 10.22 to an integer * 0x1e3c68 is a magical rounding constant that produces slightly * better results than 0x200000. */ return (number * flt2.i + 0x1e3c68) >> 22; } /** * clutter_fixed_qmulx: * @op1: #ClutterFixed * @op2: #ClutterFixed * * Return value: #ClutterFixed. * * Multiplies two fixed values using 64bit arithmetic; this provides * significantly better precission than the #CLUTTER_FIXED_MUL macro, * but at performance cost (about 2.7 times slowdown on ARMv5e, and 2 times * on x86). * * Since: 0.3 */ ClutterFixed clutter_qmulx (ClutterFixed op1, ClutterFixed op2) { #ifdef __arm__ /* This provides about 12% speedeup on the gcc -O2 optimised * C version * * Based on code found in the following thread: * http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/2006-August/014405.html */ int res_low, res_hi; __asm__ ("smull %0, %1, %2, %3 \n" "mov %0, %0, lsr %4 \n" "add %1, %0, %1, lsl %5 \n" : "=r"(res_hi), "=r"(res_low)\ : "r"(op1), "r"(op2), "i"(CFX_Q), "i"(32-CFX_Q)); return (ClutterFixed) res_low; #else long long r = (long long) op1 * (long long) op2; return (unsigned int)(r >> CFX_Q); #endif } /* */ const double _magic = 68719476736.0*1.5; /* Where in the 64 bits of double is the mantisa */ #ifdef LITTLE_ENDIAN #define _CFX_MAN 0 #else #define _CFX_MAN 1 #endif /* * clutter_double_to_fixed : * @value: value to be converted * * A fast conversion from double precision floating to fixed point * * Return value: Fixed point representation of the value * * Since: 0.2 */ ClutterFixed _clutter_double_to_fixed (double val) { union { double d; unsigned int i[2]; } dbl; dbl.d = val; dbl.d = dbl.d + _magic; return dbl.i[0]; } /* * clutter_double_to_int : * @value: value to be converted * * A fast conversion from doulbe precision floatint point to int; * used this instead of casting double/float to int. * * Return value: Integer part of the double * * Since: 0.2 */ ClutterFixed _clutter_double_to_int (double val) { union { double d; unsigned int i[2]; } dbl; dbl.d = val; dbl.d = dbl.d + _magic; return dbl.i[0] >> 16; } #undef _CFX_MAN