diff options
Diffstat (limited to 'libc/startup')
| -rw-r--r-- | libc/startup/baremetal/arm/start.cpp | 27 |
1 files changed, 18 insertions, 9 deletions
diff --git a/libc/startup/baremetal/arm/start.cpp b/libc/startup/baremetal/arm/start.cpp index 4740067..db89828 100644 --- a/libc/startup/baremetal/arm/start.cpp +++ b/libc/startup/baremetal/arm/start.cpp @@ -131,20 +131,30 @@ namespace LIBC_NAMESPACE_DECL { __arm_wsr("CPSR_c", 0x13); // SVC #endif -#ifdef __ARM_FP -// Enable FPU -#if __ARM_ARCH_PROFILE == 'M' +#if __ARM_ARCH_PROFILE == 'M' && \ + (defined(__ARM_FP) || defined(__ARM_FEATURE_MVE)) + // Enable FPU and MVE. They can't be enabled independently: the two are + // governed by the same bits in CPACR. // Based on // https://developer.arm.com/documentation/dui0646/c/Cortex-M7-Peripherals/Floating-Point-Unit/Enabling-the-FPU - // Set CPACR cp10 and cp11 - auto cpacr = (volatile uint32_t *const)0xE000ED88; + // Set CPACR cp10 and cp11. + auto cpacr = reinterpret_cast<volatile uint32_t *const>(0xE000ED88); *cpacr |= (0xF << 20); __dsb(0xF); __isb(0xF); -#elif __ARM_ARCH_PROFILE == 'A' || __ARM_ARCH_PROFILE == 'R' +#if defined(__ARM_FEATURE_MVE) + // Initialize low-overhead-loop tail predication to its neutral state + uint32_t fpscr; + __asm__ __volatile__("vmrs %0, FPSCR" : "=r"(fpscr) : :); + fpscr |= (0x4 << 16); + __asm__ __volatile__("vmsr FPSCR, %0" : : "r"(fpscr) :); +#endif +#elif (__ARM_ARCH_PROFILE == 'A' || __ARM_ARCH_PROFILE == 'R') && \ + defined(__ARM_FP) + // Enable FPU. // Based on // https://developer.arm.com/documentation/dui0472/m/Compiler-Coding-Practices/Enabling-NEON-and-FPU-for-bare-metal - // Set CPACR cp10 and cp11 + // Set CPACR cp10 and cp11. uint32_t cpacr = __arm_rsr("p15:0:c1:c0:2"); cpacr |= (0xF << 20); __arm_wsr("p15:0:c1:c0:2", cpacr); @@ -152,10 +162,9 @@ namespace LIBC_NAMESPACE_DECL { // Set FPEXC.EN uint32_t fpexc; __asm__ __volatile__("vmrs %0, FPEXC" : "=r"(fpexc) : :); - fpexc |= (1 << 30); + fpexc |= (0x1 << 30); __asm__ __volatile__("vmsr FPEXC, %0" : : "r"(fpexc) :); #endif -#endif // Perform the equivalent of scatterloading LIBC_NAMESPACE::memcpy(__data_start, __data_source, |