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Assembler version 1: use roll and bit clear instructions 

Former-commit-id: 4f27d34dd63c635a65ee33f2c368978d5b162974
This commit is contained in:
David Brodski 2014-09-19 02:00:32 +02:00
parent d41857e626
commit 961bef22f5
2 changed files with 53 additions and 1 deletions
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53
libsrc/leddevice/LedDeviceWS2812b.cpp
View File

@ -260,6 +260,31 @@ LedDeviceWS2812b::LedDeviceWS2812b() :
printf("WS2812b init finished \n");
}
#ifdef WS2812_ASM_OPTI
// rotate register, used to move the 1 around :-)
static inline __attribute__((always_inline))
uint32_t arm_ror_imm(uint32_t v, uint32_t sh) {
uint32_t d;
asm ("ROR %[Rd], %[Rm], %[Is]" : [Rd] "=r" (d) : [Rm] "r" (v), [Is] "i" (sh));
return d;
}
static inline __attribute__((always_inline))
uint32_t arm_ror(uint32_t v, uint32_t sh) {
uint32_t d;
asm ("ROR %[Rd], %[Rm], %[Rs]" : [Rd] "=r" (d) : [Rm] "r" (v), [Rs] "r" (sh));
return d;
}
static inline __attribute__((always_inline))
uint32_t arm_Bit_Clear_imm(uint32_t v, uint32_t v2) {
uint32_t d;
asm ("BIC %[Rd], %[Rm], %[Rs]" : [Rd] "=r" (d) : [Rm] "r" (v), [Rs] "r" (v2));
return d;
}
#endif
int LedDeviceWS2812b::write(const std::vector<ColorRgb> &ledValues)
{
@ -295,6 +320,9 @@ int LedDeviceWS2812b::write(const std::vector<ColorRgb> &ledValues)
//mLedCount = (NUM_DATA_WORDS - 1) / 2.25;
}
#ifdef WS2812_ASM_OPTI
unsigned int startbitPattern = 0x40000000; // = 0100 0000 0000 0000 0000 0000 0000 0000 pattern
#endif
for(size_t i=0; i<mLedCount; i++) {
@ -306,10 +334,26 @@ int LedDeviceWS2812b::write(const std::vector<ColorRgb> &ledValues)
// Iterate through color bits to get wire bits
for(int j=23; j>=0; j--) {
unsigned char colorBit = (colorBits & (1 << j)) ? 1 : 0; // Holds current bit out of colorBits to be processed
#ifdef WS2812_ASM_OPTI
// Fetch word the bit is in
unsigned int wordOffset = (int)(wireBit / 32);
wireBit +=3;
// printBinary(startbitPattern, 32);
// printf(" %d\n", j);
if (colorBits & (1 << j)) {
PWMWaveform[wordOffset] |= startbitPattern;
} else {
PWMWaveform[wordOffset] = arm_Bit_Clear_imm(PWMWaveform[wordOffset], startbitPattern);
}
startbitPattern = arm_ror_imm(startbitPattern, 3);
#else
unsigned char colorBit = (colorBits & (1 << j)) ? 1 : 0; // Holds current bit out of colorBits to be processed
setPWMBit(wireBit, colorBit);
wireBit +=3;
#endif
/* old code for better understanding
switch(colorBit) {
case 1:
@ -328,6 +372,11 @@ int LedDeviceWS2812b::write(const std::vector<ColorRgb> &ledValues)
}
}
#ifdef WS2812_ASM_OPTI
// calculate the bits manually since it is not needed with asm
//wireBit += mLedCount * 24 *3;
//printf(" %d\n", wireBit);
#endif
//remove one to undo optimization
wireBit --;
@ -344,6 +393,8 @@ int LedDeviceWS2812b::write(const std::vector<ColorRgb> &ledValues)
wireBit += 3;
}
// printBinary(PWMWaveform[(int)(oldwireBitValue / 32) -1 ], 32);
// printf(" post\n");
// printBinary(PWMWaveform[(int)(oldwireBitValue / 32)], 32);
// printf(" post\n");

1
libsrc/leddevice/LedDeviceWS2812b.h
View File

@ -102,6 +102,7 @@
#include <leddevice/LedDevice.h>
#define BENCHMARK
#define WS2812_ASM_OPTI
// The page map contains pointers to memory that we will allocate below. It uses two pointers
// per address. This is because the software (this program) deals only in virtual addresses,