15.spi与硬件浮点

15.开启硬件浮点

解决浮点计算

/** @description	: 使能I.MX6U的硬件NEON和FPU* @param 		: 无* @return 		: 无*/void imx6ul_hardfpu_enable(void)
{uint32_t cpacr;uint32_t fpexc;/* 使能NEON和FPU */cpacr = __get_CPACR();cpacr = (cpacr & ~(CPACR_ASEDIS_Msk | CPACR_D32DIS_Msk))|  (3UL << CPACR_cp10_Pos) | (3UL << CPACR_cp11_Pos);__set_CPACR(cpacr);fpexc = __get_FPEXC();fpexc |= 0x40000000UL;	__set_FPEXC(fpexc);
}

在mian函数中调用上述代码imx6ul_hardfpu_enable()

makefile

$(COBJS) : obj/%.o : %.c$(CC) -Wall -march=armv7-a -mfpu=neon-vfpv4 -mfloat-abi=hard  -Wa,-mimplicit-it=thumb -nostdlib -fno-builtin  -c -O2  $(INCLUDE) -o $@ $<

-Wall -Wa 之间添加-march=armv7-a -mfpu=neon-vfpv4 -mfloat-abi=hard