%% options copyright owner = Dirk Krause copyright year = 2017-xxxx SPDX-License-Identifier: BSD-3-Clause %% header /** @file dk4pxbit.h Bit constants for pixels. */ #ifndef DK4CONF_H_INCLUDED #if DK4_BUILDING_DKTOOLS4 #include "dk4conf.h" #else #include #endif #endif #ifndef DK4TYPES_H_INCLUDED #if DK4_BUILDING_DKTOOLS4 #include "dk4types.h" #else #include #endif #endif #ifndef DK4PX_H_INCLUDED #if DK4_BUILDING_DKTOOLS4 #include "dk4px.h" #else #include #endif #endif #ifdef __cplusplus extern "C" { #endif /** Retrieve bit for a given bit number. Least significant bit is 0, most significant is 15. @param bitno Bit number to retrieve bit value for. @return Positive bit value on success, 0 on error (out of range). */ dk4_px_t dk4pxbit_get_bit(size_t bitno); /** Retrieve maximum value for a given bit number. Least significant bit is 0, most significant is 15. @param bitno Bit number to retrieve bit value for. @return Positive maximum value on success, 0 on error (out of range). */ dk4_px_t dk4pxbit_get_max(size_t bitno); /** Find bit number to represent a maximum value. @param maxval Maximum value for a pixel component. @return Required bit number. */ size_t dk4pxbit_get_bitno(dk4_px_t maxval); #ifdef __cplusplus } #endif /* vim: set ai sw=4 ts=4 : */ %% module #include "dk4conf.h" #ifndef DK4PXBIT_H_INCLUDED #include "dk4pxbit.h" #endif $!trace-include /** Bit number values. */ static dk4_px_t dk4pxbit_values[] = { 0x0001U, 0x0002U, 0x0004U, 0x0008U, 0x0010U, 0x0020U, 0x0040U, 0x0080U, 0x0100U, 0x0200U, 0x0400U, 0x0800U, 0x1000U, 0x2000U, 0x4000U, 0x8000U }; /** Maxima values. */ static dk4_px_t dk4pxbit_maxima[] = { 0x0001U, 0x0003U, 0x0007U, 0x000FU, 0x001FU, 0x003FU, 0x007FU, 0x00FFU, 0x01FFU, 0x03FFU, 0x07FFU, 0x0FFFU, 0x1FFFU, 0x3FFFU, 0x7FFFU, 0xFFFFU }; dk4_px_t dk4pxbit_get_bit(size_t bitno) { if ((sizeof(dk4pxbit_values)/sizeof(dk4_px_t)) > bitno) { return (dk4pxbit_values[bitno]); } return ((dk4_px_t)0U); } dk4_px_t dk4pxbit_get_max(size_t bitno) { dk4_px_t back = 0; $? "+ dk4pxbit_get_max %u", (unsigned)bitno if (((sizeof(dk4pxbit_maxima)/sizeof(dk4_px_t)) > bitno) && (0 < bitno)) { back = dk4pxbit_maxima[bitno - 1]; } $? "- dk4pxbit_get_max %lu", (unsigned long)back return back; } size_t dk4pxbit_get_bitno(dk4_px_t maxval) { size_t back = 16; size_t i = 15; int cc = 1; for (i = 15; ((i > 0) && (1 == cc)); i--) { if (dk4pxbit_maxima[i - 1] >= maxval) { back = i; } else { cc = 0; } } return back; } /* vim: set ai sw=4 ts=4 : */