543 lines
18 KiB
C
543 lines
18 KiB
C
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#ifndef __INC_LIB8TION_SCALE_H
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#define __INC_LIB8TION_SCALE_H
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///@ingroup lib8tion
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///@defgroup Scaling Scaling functions
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/// Fast, efficient 8-bit scaling functions specifically
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/// designed for high-performance LED programming.
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///
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/// Because of the AVR(Arduino) and ARM assembly language
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/// implementations provided, using these functions often
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/// results in smaller and faster code than the equivalent
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/// program using plain "C" arithmetic and logic.
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///@{
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/// scale one byte by a second one, which is treated as
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/// the numerator of a fraction whose denominator is 256
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/// In other words, it computes i * (scale / 256)
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/// 4 clocks AVR with MUL, 2 clocks ARM
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LIB8STATIC_ALWAYS_INLINE uint8_t scale8( uint8_t i, fract8 scale)
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{
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#if SCALE8_C == 1
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#if (FASTLED_SCALE8_FIXED == 1)
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return (((uint16_t)i) * (1+(uint16_t)(scale))) >> 8;
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#else
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return ((uint16_t)i * (uint16_t)(scale) ) >> 8;
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#endif
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#elif SCALE8_AVRASM == 1
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#if defined(LIB8_ATTINY)
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#if (FASTLED_SCALE8_FIXED == 1)
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uint8_t work=i;
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#else
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uint8_t work=0;
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#endif
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uint8_t cnt=0x80;
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asm volatile(
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#if (FASTLED_SCALE8_FIXED == 1)
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" inc %[scale] \n\t"
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" breq DONE_%= \n\t"
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" clr %[work] \n\t"
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#endif
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"LOOP_%=: \n\t"
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/*" sbrc %[scale], 0 \n\t"
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" add %[work], %[i] \n\t"
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" ror %[work] \n\t"
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" lsr %[scale] \n\t"
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" clc \n\t"*/
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" sbrc %[scale], 0 \n\t"
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" add %[work], %[i] \n\t"
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" ror %[work] \n\t"
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" lsr %[scale] \n\t"
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" lsr %[cnt] \n\t"
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"brcc LOOP_%= \n\t"
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"DONE_%=: \n\t"
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: [work] "+r" (work), [cnt] "+r" (cnt)
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: [scale] "r" (scale), [i] "r" (i)
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:
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);
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return work;
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#else
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asm volatile(
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#if (FASTLED_SCALE8_FIXED==1)
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// Multiply 8-bit i * 8-bit scale, giving 16-bit r1,r0
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"mul %0, %1 \n\t"
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// Add i to r0, possibly setting the carry flag
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"add r0, %0 \n\t"
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// load the immediate 0 into i (note, this does _not_ touch any flags)
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"ldi %0, 0x00 \n\t"
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// walk and chew gum at the same time
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"adc %0, r1 \n\t"
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#else
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/* Multiply 8-bit i * 8-bit scale, giving 16-bit r1,r0 */
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"mul %0, %1 \n\t"
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/* Move the high 8-bits of the product (r1) back to i */
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"mov %0, r1 \n\t"
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/* Restore r1 to "0"; it's expected to always be that */
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#endif
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"clr __zero_reg__ \n\t"
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: "+a" (i) /* writes to i */
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: "a" (scale) /* uses scale */
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: "r0", "r1" /* clobbers r0, r1 */ );
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/* Return the result */
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return i;
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#endif
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#else
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#error "No implementation for scale8 available."
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#endif
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}
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/// The "video" version of scale8 guarantees that the output will
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/// be only be zero if one or both of the inputs are zero. If both
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/// inputs are non-zero, the output is guaranteed to be non-zero.
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/// This makes for better 'video'/LED dimming, at the cost of
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/// several additional cycles.
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LIB8STATIC_ALWAYS_INLINE uint8_t scale8_video( uint8_t i, fract8 scale)
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{
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#if SCALE8_C == 1 || defined(LIB8_ATTINY)
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uint8_t j = (((int)i * (int)scale) >> 8) + ((i&&scale)?1:0);
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// uint8_t nonzeroscale = (scale != 0) ? 1 : 0;
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// uint8_t j = (i == 0) ? 0 : (((int)i * (int)(scale) ) >> 8) + nonzeroscale;
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return j;
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#elif SCALE8_AVRASM == 1
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uint8_t j=0;
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asm volatile(
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" tst %[i]\n\t"
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" breq L_%=\n\t"
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" mul %[i], %[scale]\n\t"
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" mov %[j], r1\n\t"
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" clr __zero_reg__\n\t"
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" cpse %[scale], r1\n\t"
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" subi %[j], 0xFF\n\t"
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"L_%=: \n\t"
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: [j] "+a" (j)
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: [i] "a" (i), [scale] "a" (scale)
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: "r0", "r1");
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return j;
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// uint8_t nonzeroscale = (scale != 0) ? 1 : 0;
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// asm volatile(
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// " tst %0 \n"
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// " breq L_%= \n"
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// " mul %0, %1 \n"
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// " mov %0, r1 \n"
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// " add %0, %2 \n"
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// " clr __zero_reg__ \n"
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// "L_%=: \n"
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// : "+a" (i)
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// : "a" (scale), "a" (nonzeroscale)
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// : "r0", "r1");
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// // Return the result
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// return i;
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#else
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#error "No implementation for scale8_video available."
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#endif
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}
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/// This version of scale8 does not clean up the R1 register on AVR
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/// If you are doing several 'scale8's in a row, use this, and
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/// then explicitly call cleanup_R1.
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LIB8STATIC_ALWAYS_INLINE uint8_t scale8_LEAVING_R1_DIRTY( uint8_t i, fract8 scale)
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{
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#if SCALE8_C == 1
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#if (FASTLED_SCALE8_FIXED == 1)
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return (((uint16_t)i) * ((uint16_t)(scale)+1)) >> 8;
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#else
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return ((int)i * (int)(scale) ) >> 8;
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#endif
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#elif SCALE8_AVRASM == 1
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asm volatile(
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#if (FASTLED_SCALE8_FIXED==1)
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// Multiply 8-bit i * 8-bit scale, giving 16-bit r1,r0
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"mul %0, %1 \n\t"
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// Add i to r0, possibly setting the carry flag
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"add r0, %0 \n\t"
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// load the immediate 0 into i (note, this does _not_ touch any flags)
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"ldi %0, 0x00 \n\t"
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// walk and chew gum at the same time
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"adc %0, r1 \n\t"
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#else
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/* Multiply 8-bit i * 8-bit scale, giving 16-bit r1,r0 */
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"mul %0, %1 \n\t"
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/* Move the high 8-bits of the product (r1) back to i */
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"mov %0, r1 \n\t"
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#endif
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/* R1 IS LEFT DIRTY HERE; YOU MUST ZERO IT OUT YOURSELF */
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/* "clr __zero_reg__ \n\t" */
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: "+a" (i) /* writes to i */
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: "a" (scale) /* uses scale */
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: "r0", "r1" /* clobbers r0, r1 */ );
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// Return the result
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return i;
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#else
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#error "No implementation for scale8_LEAVING_R1_DIRTY available."
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#endif
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}
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/// This version of scale8_video does not clean up the R1 register on AVR
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/// If you are doing several 'scale8_video's in a row, use this, and
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/// then explicitly call cleanup_R1.
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LIB8STATIC_ALWAYS_INLINE uint8_t scale8_video_LEAVING_R1_DIRTY( uint8_t i, fract8 scale)
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{
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#if SCALE8_C == 1 || defined(LIB8_ATTINY)
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uint8_t j = (((int)i * (int)scale) >> 8) + ((i&&scale)?1:0);
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// uint8_t nonzeroscale = (scale != 0) ? 1 : 0;
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// uint8_t j = (i == 0) ? 0 : (((int)i * (int)(scale) ) >> 8) + nonzeroscale;
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return j;
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#elif SCALE8_AVRASM == 1
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uint8_t j=0;
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asm volatile(
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" tst %[i]\n\t"
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" breq L_%=\n\t"
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" mul %[i], %[scale]\n\t"
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" mov %[j], r1\n\t"
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" breq L_%=\n\t"
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" subi %[j], 0xFF\n\t"
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"L_%=: \n\t"
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: [j] "+a" (j)
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: [i] "a" (i), [scale] "a" (scale)
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: "r0", "r1");
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return j;
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// uint8_t nonzeroscale = (scale != 0) ? 1 : 0;
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// asm volatile(
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// " tst %0 \n"
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// " breq L_%= \n"
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// " mul %0, %1 \n"
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// " mov %0, r1 \n"
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// " add %0, %2 \n"
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// " clr __zero_reg__ \n"
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// "L_%=: \n"
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// : "+a" (i)
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// : "a" (scale), "a" (nonzeroscale)
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// : "r0", "r1");
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// // Return the result
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// return i;
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#else
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#error "No implementation for scale8_video_LEAVING_R1_DIRTY available."
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#endif
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}
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/// Clean up the r1 register after a series of *LEAVING_R1_DIRTY calls
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LIB8STATIC_ALWAYS_INLINE void cleanup_R1(void)
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{
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#if CLEANUP_R1_AVRASM == 1
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// Restore r1 to "0"; it's expected to always be that
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asm volatile( "clr __zero_reg__ \n\t" : : : "r1" );
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#endif
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}
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/// scale a 16-bit unsigned value by an 8-bit value,
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/// considered as numerator of a fraction whose denominator
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/// is 256. In other words, it computes i * (scale / 256)
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LIB8STATIC_ALWAYS_INLINE uint16_t scale16by8( uint16_t i, fract8 scale )
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{
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#if SCALE16BY8_C == 1
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uint16_t result;
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#if FASTLED_SCALE8_FIXED == 1
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result = (i * (1+((uint16_t)scale))) >> 8;
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#else
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result = (i * scale) / 256;
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#endif
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return result;
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#elif SCALE16BY8_AVRASM == 1
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#if FASTLED_SCALE8_FIXED == 1
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uint16_t result = 0;
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asm volatile(
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// result.A = HighByte( (i.A x scale) + i.A )
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" mul %A[i], %[scale] \n\t"
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" add r0, %A[i] \n\t"
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// " adc r1, [zero] \n\t"
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// " mov %A[result], r1 \n\t"
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" adc %A[result], r1 \n\t"
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// result.A-B += i.B x scale
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" mul %B[i], %[scale] \n\t"
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" add %A[result], r0 \n\t"
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" adc %B[result], r1 \n\t"
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// cleanup r1
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" clr __zero_reg__ \n\t"
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// result.A-B += i.B
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" add %A[result], %B[i] \n\t"
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" adc %B[result], __zero_reg__ \n\t"
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: [result] "+r" (result)
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: [i] "r" (i), [scale] "r" (scale)
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: "r0", "r1"
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);
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return result;
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#else
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uint16_t result = 0;
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asm volatile(
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// result.A = HighByte(i.A x j )
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" mul %A[i], %[scale] \n\t"
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" mov %A[result], r1 \n\t"
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//" clr %B[result] \n\t"
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// result.A-B += i.B x j
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" mul %B[i], %[scale] \n\t"
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" add %A[result], r0 \n\t"
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" adc %B[result], r1 \n\t"
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// cleanup r1
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" clr __zero_reg__ \n\t"
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: [result] "+r" (result)
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: [i] "r" (i), [scale] "r" (scale)
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: "r0", "r1"
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);
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return result;
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#endif
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#else
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#error "No implementation for scale16by8 available."
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#endif
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}
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/// scale a 16-bit unsigned value by a 16-bit value,
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/// considered as numerator of a fraction whose denominator
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/// is 65536. In other words, it computes i * (scale / 65536)
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LIB8STATIC uint16_t scale16( uint16_t i, fract16 scale )
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{
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#if SCALE16_C == 1
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uint16_t result;
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#if FASTLED_SCALE8_FIXED == 1
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result = ((uint32_t)(i) * (1+(uint32_t)(scale))) / 65536;
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#else
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result = ((uint32_t)(i) * (uint32_t)(scale)) / 65536;
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#endif
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return result;
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#elif SCALE16_AVRASM == 1
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#if FASTLED_SCALE8_FIXED == 1
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// implemented sort of like
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// result = ((i * scale) + i ) / 65536
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//
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// why not like this, you may ask?
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// result = (i * (scale+1)) / 65536
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// the answer is that if scale is 65535, then scale+1
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// will be zero, which is not what we want.
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uint32_t result;
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asm volatile(
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// result.A-B = i.A x scale.A
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" mul %A[i], %A[scale] \n\t"
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// save results...
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// basic idea:
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//" mov %A[result], r0 \n\t"
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//" mov %B[result], r1 \n\t"
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// which can be written as...
|
||
|
|
" movw %A[result], r0 \n\t"
|
||
|
|
// Because we're going to add i.A-B to
|
||
|
|
// result.A-D, we DO need to keep both
|
||
|
|
// the r0 and r1 portions of the product
|
||
|
|
// UNlike in the 'unfixed scale8' version.
|
||
|
|
// So the movw here is needed.
|
||
|
|
: [result] "=r" (result)
|
||
|
|
: [i] "r" (i),
|
||
|
|
[scale] "r" (scale)
|
||
|
|
: "r0", "r1"
|
||
|
|
);
|
||
|
|
|
||
|
|
asm volatile(
|
||
|
|
// result.C-D = i.B x scale.B
|
||
|
|
" mul %B[i], %B[scale] \n\t"
|
||
|
|
//" mov %C[result], r0 \n\t"
|
||
|
|
//" mov %D[result], r1 \n\t"
|
||
|
|
" movw %C[result], r0 \n\t"
|
||
|
|
: [result] "+r" (result)
|
||
|
|
: [i] "r" (i),
|
||
|
|
[scale] "r" (scale)
|
||
|
|
: "r0", "r1"
|
||
|
|
);
|
||
|
|
|
||
|
|
const uint8_t zero = 0;
|
||
|
|
asm volatile(
|
||
|
|
// result.B-D += i.B x scale.A
|
||
|
|
" mul %B[i], %A[scale] \n\t"
|
||
|
|
|
||
|
|
" add %B[result], r0 \n\t"
|
||
|
|
" adc %C[result], r1 \n\t"
|
||
|
|
" adc %D[result], %[zero] \n\t"
|
||
|
|
|
||
|
|
// result.B-D += i.A x scale.B
|
||
|
|
" mul %A[i], %B[scale] \n\t"
|
||
|
|
|
||
|
|
" add %B[result], r0 \n\t"
|
||
|
|
" adc %C[result], r1 \n\t"
|
||
|
|
" adc %D[result], %[zero] \n\t"
|
||
|
|
|
||
|
|
// cleanup r1
|
||
|
|
" clr r1 \n\t"
|
||
|
|
|
||
|
|
: [result] "+r" (result)
|
||
|
|
: [i] "r" (i),
|
||
|
|
[scale] "r" (scale),
|
||
|
|
[zero] "r" (zero)
|
||
|
|
: "r0", "r1"
|
||
|
|
);
|
||
|
|
|
||
|
|
asm volatile(
|
||
|
|
// result.A-D += i.A-B
|
||
|
|
" add %A[result], %A[i] \n\t"
|
||
|
|
" adc %B[result], %B[i] \n\t"
|
||
|
|
" adc %C[result], %[zero] \n\t"
|
||
|
|
" adc %D[result], %[zero] \n\t"
|
||
|
|
: [result] "+r" (result)
|
||
|
|
: [i] "r" (i),
|
||
|
|
[zero] "r" (zero)
|
||
|
|
);
|
||
|
|
|
||
|
|
result = result >> 16;
|
||
|
|
return result;
|
||
|
|
#else
|
||
|
|
uint32_t result;
|
||
|
|
asm volatile(
|
||
|
|
// result.A-B = i.A x scale.A
|
||
|
|
" mul %A[i], %A[scale] \n\t"
|
||
|
|
// save results...
|
||
|
|
// basic idea:
|
||
|
|
//" mov %A[result], r0 \n\t"
|
||
|
|
//" mov %B[result], r1 \n\t"
|
||
|
|
// which can be written as...
|
||
|
|
" movw %A[result], r0 \n\t"
|
||
|
|
// We actually don't need to do anything with r0,
|
||
|
|
// as result.A is never used again here, so we
|
||
|
|
// could just move the high byte, but movw is
|
||
|
|
// one clock cycle, just like mov, so might as
|
||
|
|
// well, in case we want to use this code for
|
||
|
|
// a generic 16x16 multiply somewhere.
|
||
|
|
|
||
|
|
: [result] "=r" (result)
|
||
|
|
: [i] "r" (i),
|
||
|
|
[scale] "r" (scale)
|
||
|
|
: "r0", "r1"
|
||
|
|
);
|
||
|
|
|
||
|
|
asm volatile(
|
||
|
|
// result.C-D = i.B x scale.B
|
||
|
|
" mul %B[i], %B[scale] \n\t"
|
||
|
|
//" mov %C[result], r0 \n\t"
|
||
|
|
//" mov %D[result], r1 \n\t"
|
||
|
|
" movw %C[result], r0 \n\t"
|
||
|
|
: [result] "+r" (result)
|
||
|
|
: [i] "r" (i),
|
||
|
|
[scale] "r" (scale)
|
||
|
|
: "r0", "r1"
|
||
|
|
);
|
||
|
|
|
||
|
|
const uint8_t zero = 0;
|
||
|
|
asm volatile(
|
||
|
|
// result.B-D += i.B x scale.A
|
||
|
|
" mul %B[i], %A[scale] \n\t"
|
||
|
|
|
||
|
|
" add %B[result], r0 \n\t"
|
||
|
|
" adc %C[result], r1 \n\t"
|
||
|
|
" adc %D[result], %[zero] \n\t"
|
||
|
|
|
||
|
|
// result.B-D += i.A x scale.B
|
||
|
|
" mul %A[i], %B[scale] \n\t"
|
||
|
|
|
||
|
|
" add %B[result], r0 \n\t"
|
||
|
|
" adc %C[result], r1 \n\t"
|
||
|
|
" adc %D[result], %[zero] \n\t"
|
||
|
|
|
||
|
|
// cleanup r1
|
||
|
|
" clr r1 \n\t"
|
||
|
|
|
||
|
|
: [result] "+r" (result)
|
||
|
|
: [i] "r" (i),
|
||
|
|
[scale] "r" (scale),
|
||
|
|
[zero] "r" (zero)
|
||
|
|
: "r0", "r1"
|
||
|
|
);
|
||
|
|
|
||
|
|
result = result >> 16;
|
||
|
|
return result;
|
||
|
|
#endif
|
||
|
|
#else
|
||
|
|
#error "No implementation for scale16 available."
|
||
|
|
#endif
|
||
|
|
}
|
||
|
|
///@}
|
||
|
|
|
||
|
|
///@defgroup Dimming Dimming and brightening functions
|
||
|
|
///
|
||
|
|
/// Dimming and brightening functions
|
||
|
|
///
|
||
|
|
/// The eye does not respond in a linear way to light.
|
||
|
|
/// High speed PWM'd LEDs at 50% duty cycle appear far
|
||
|
|
/// brighter then the 'half as bright' you might expect.
|
||
|
|
///
|
||
|
|
/// If you want your midpoint brightness leve (128) to
|
||
|
|
/// appear half as bright as 'full' brightness (255), you
|
||
|
|
/// have to apply a 'dimming function'.
|
||
|
|
///@{
|
||
|
|
|
||
|
|
/// Adjust a scaling value for dimming
|
||
|
|
LIB8STATIC uint8_t dim8_raw( uint8_t x)
|
||
|
|
{
|
||
|
|
return scale8( x, x);
|
||
|
|
}
|
||
|
|
|
||
|
|
/// Adjust a scaling value for dimming for video (value will never go below 1)
|
||
|
|
LIB8STATIC uint8_t dim8_video( uint8_t x)
|
||
|
|
{
|
||
|
|
return scale8_video( x, x);
|
||
|
|
}
|
||
|
|
|
||
|
|
/// Linear version of the dimming function that halves for values < 128
|
||
|
|
LIB8STATIC uint8_t dim8_lin( uint8_t x )
|
||
|
|
{
|
||
|
|
if( x & 0x80 ) {
|
||
|
|
x = scale8( x, x);
|
||
|
|
} else {
|
||
|
|
x += 1;
|
||
|
|
x /= 2;
|
||
|
|
}
|
||
|
|
return x;
|
||
|
|
}
|
||
|
|
|
||
|
|
/// inverse of the dimming function, brighten a value
|
||
|
|
LIB8STATIC uint8_t brighten8_raw( uint8_t x)
|
||
|
|
{
|
||
|
|
uint8_t ix = 255 - x;
|
||
|
|
return 255 - scale8( ix, ix);
|
||
|
|
}
|
||
|
|
|
||
|
|
/// inverse of the dimming function, brighten a value
|
||
|
|
LIB8STATIC uint8_t brighten8_video( uint8_t x)
|
||
|
|
{
|
||
|
|
uint8_t ix = 255 - x;
|
||
|
|
return 255 - scale8_video( ix, ix);
|
||
|
|
}
|
||
|
|
|
||
|
|
/// inverse of the dimming function, brighten a value
|
||
|
|
LIB8STATIC uint8_t brighten8_lin( uint8_t x )
|
||
|
|
{
|
||
|
|
uint8_t ix = 255 - x;
|
||
|
|
if( ix & 0x80 ) {
|
||
|
|
ix = scale8( ix, ix);
|
||
|
|
} else {
|
||
|
|
ix += 1;
|
||
|
|
ix /= 2;
|
||
|
|
}
|
||
|
|
return 255 - ix;
|
||
|
|
}
|
||
|
|
|
||
|
|
///@}
|
||
|
|
#endif
|