我正在尝试有效地从 RGB 转换为灰度，所以我从 here 得到了一个函数其中解释了如何从 RGBA 转换为灰度。现在我正在尝试做同样的事情，但只使用 RGB。我改变了一些东西，但似乎效果不佳。我不知道为什么，有人看到我的错误吗？
void neon_asm_convert(uint8_t * __restrict dest, uint8_t * __restrict src, int numPixels)
{
__asm__ volatile(
"lsr %2, %2, #3 \n"
"# build the three constants: \n"
"mov r4, #28 \n" // Blue channel multiplier
"mov r5, #151 \n" // Green channel multiplier
"mov r6, #77 \n" // Red channel multiplier
"vdup.8 d4, r4 \n"
"vdup.8 d5, r5 \n"
"vdup.8 d6, r6 \n"
"0: \n"
"# load 8 pixels: \n" //RGBR
"vld4.8 {d0-d3}, [%1]! \n"
"# do the weight average: \n"
"vmull.u8 q7, d0, d4 \n"
"vmlal.u8 q7, d1, d5 \n"
"vmlal.u8 q7, d2, d6 \n"
"# shift and store: \n"
"vshrn.u16 d7, q7, #8 \n" // Divide q3 by 256 and store in the d7
"vst1.8 {d7}, [%0]! \n"
"subs %2, %2, #1 \n" // Decrement iteration count
"# load 8 pixels: \n"
"vld4.8 {d8-d11}, [%1]! \n" //Other GBRG
"# do the weight average: \n"
"vmull.u8 q7, d3, d4 \n"
"vmlal.u8 q7, d8, d5 \n"
"vmlal.u8 q7, d9, d6 \n"
"# shift and store: \n"
"vshrn.u16 d7, q7, #8 \n" // Divide q3 by 256 and store in the d7
"vst1.8 {d7}, [%0]! \n"
"subs %2, %2, #1 \n" // Decrement iteration count
"# load 8 pixels: \n"
"vld4.8 {d0-d3}, [%1]! \n"
"# do the weight average: \n"
"vmull.u8 q7, d10, d4 \n"
"vmlal.u8 q7, d11, d5 \n"
"vmlal.u8 q7, d0, d6 \n"
"# shift and store: \n"
"vshrn.u16 d7, q7, #8 \n" // Divide q3 by 256 and store in the d7
"vst1.8 {d7}, [%0]! \n"
"subs %2, %2, #1 \n" // Decrement iteration count
"# do the weight average: \n"
"vmull.u8 q7, d1, d4 \n"
"vmlal.u8 q7, d2, d5 \n"
"vmlal.u8 q7, d3, d6 \n"
"# shift and store: \n"
"vshrn.u16 d7, q7, #8 \n" // Divide q3 by 256 and store in the d7
"vst1.8 {d7}, [%0]! \n"
"subs %2, %2, #1 \n" // Decrement iteration count
"bne 0b \n" // Repeat unil iteration count is not zero
:
: "r"(dest), "r"(src), "r"(numPixels)
: "r4", "r5", "r6"
);
}
最佳答案
您应该使用“vld3.8 {d0-d2}，[%1]!\n”
关于assembly - 使用arm neon进行RGB到灰度转换，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/8501987/