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a407285ff2
Ensure unsigned integers are used instead of signed ones when performing left bit shifts. This has been detected by the Undefined Behaviour Sanitizer (UBSan). Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io> Signed-off-by: Juan A. Suarez Romero <jasuarez@igalia.com> Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/29772>
120 lines
4.1 KiB
C
120 lines
4.1 KiB
C
/*
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* Copyright (C) 2011 Marek Olšák <maraeo@gmail.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is 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
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* THE 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
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*/
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/* Copied from EXT_texture_shared_exponent and edited, getting rid of
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* expensive float math bits too. */
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#ifndef RGB9E5_H
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#define RGB9E5_H
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#include <assert.h>
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#include <stdint.h>
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#include <math.h>
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#define RGB9E5_EXPONENT_BITS 5
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#define RGB9E5_MANTISSA_BITS 9
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#define RGB9E5_EXP_BIAS 15
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#define RGB9E5_MAX_VALID_BIASED_EXP 31
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#define MAX_RGB9E5_EXP (RGB9E5_MAX_VALID_BIASED_EXP - RGB9E5_EXP_BIAS)
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#define RGB9E5_MANTISSA_VALUES (1<<RGB9E5_MANTISSA_BITS)
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#define MAX_RGB9E5_MANTISSA (RGB9E5_MANTISSA_VALUES-1)
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#define MAX_RGB9E5 (((float)MAX_RGB9E5_MANTISSA)/RGB9E5_MANTISSA_VALUES * (1<<MAX_RGB9E5_EXP))
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static inline int rgb9e5_ClampRange(float x)
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{
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union { float f; uint32_t u; } f, max;
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f.f = x;
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max.f = MAX_RGB9E5;
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if (f.u > 0x7f800000)
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/* catches neg, NaNs */
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return 0;
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else if (f.u >= max.u)
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return max.u;
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else
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return f.u;
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}
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static inline uint32_t float3_to_rgb9e5(const float rgb[3])
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{
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int rm, gm, bm;
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uint32_t exp_shared;
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uint32_t revdenom_biasedexp;
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union { float f; uint32_t u; } rc, bc, gc, maxrgb, revdenom;
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rc.u = rgb9e5_ClampRange(rgb[0]);
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gc.u = rgb9e5_ClampRange(rgb[1]);
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bc.u = rgb9e5_ClampRange(rgb[2]);
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maxrgb.u = MAX3(rc.u, gc.u, bc.u);
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/*
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* Compared to what the spec suggests, instead of conditionally adjusting
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* the exponent after the fact do it here by doing the equivalent of +0.5 -
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* the int add will spill over into the exponent in this case.
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*/
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maxrgb.u += maxrgb.u & (1 << (23-9));
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exp_shared = MAX2((maxrgb.u >> 23), -RGB9E5_EXP_BIAS - 1 + 127) +
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1 + RGB9E5_EXP_BIAS - 127;
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revdenom_biasedexp = 127 - (exp_shared - RGB9E5_EXP_BIAS -
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RGB9E5_MANTISSA_BITS) + 1;
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revdenom.u = revdenom_biasedexp << 23;
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assert(exp_shared <= RGB9E5_MAX_VALID_BIASED_EXP);
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/*
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* The spec uses strict round-up behavior (d3d10 disagrees, but in any case
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* must match what is done above for figuring out exponent).
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* We avoid the doubles ((int) rc * revdenom + 0.5) by doing the rounding
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* ourselves (revdenom was adjusted by +1, above).
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*/
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rm = (int) (rc.f * revdenom.f);
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gm = (int) (gc.f * revdenom.f);
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bm = (int) (bc.f * revdenom.f);
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rm = (rm & 1) + (rm >> 1);
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gm = (gm & 1) + (gm >> 1);
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bm = (bm & 1) + (bm >> 1);
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assert(rm <= MAX_RGB9E5_MANTISSA);
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assert(gm <= MAX_RGB9E5_MANTISSA);
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assert(bm <= MAX_RGB9E5_MANTISSA);
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assert(rm >= 0);
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assert(gm >= 0);
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assert(bm >= 0);
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return (exp_shared << 27) | (bm << 18) | (gm << 9) | rm;
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}
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static inline void rgb9e5_to_float3(uint32_t rgb, float retval[3])
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{
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int exponent;
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union { float f; uint32_t u; } scale;
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exponent = (rgb >> 27) - RGB9E5_EXP_BIAS - RGB9E5_MANTISSA_BITS;
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scale.u = (exponent + 127) << 23;
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retval[0] = ( rgb & 0x1ff) * scale.f;
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retval[1] = ((rgb >> 9) & 0x1ff) * scale.f;
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retval[2] = ((rgb >> 18) & 0x1ff) * scale.f;
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}
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#endif
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