Created
September 20, 2018 05:15
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Atomic bitfield insert for Cortex-M3
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| #ifndef SYNC_BFI_H_839745__ | |
| #define SYNC_BFI_H_839745__ | |
| #include <stdint.h> | |
| __attribute__((always_inline)) static inline void sync_bitfield_insert(uint8_t * p, uint8_t v, int bitno) | |
| { | |
| uint8_t retval; | |
| uint8_t tmp; | |
| __asm__ volatile ("dmb ish\n" | |
| "sbfi_%=:\n\t" | |
| "ldrexb %1, [%3]\n\t" | |
| "bfi %1, %4, %5, #1\n\t" | |
| "strexb %0, %1, [%3]\n\t" | |
| "cmp %0, #0\n\t" | |
| "bne sbfi_%=\n\t" | |
| "dmb ish" | |
| : "=&r" (retval), "=&r" (tmp), "+m" (*p) | |
| : "r" (p), "r" (v), "i" (bitno) | |
| : "cc"); | |
| } | |
| #endif /* SYNC_BFI_H_839745__ */ |
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Put this together in a project, and then decided I didn't need it after all. Stashed here in a gist so that it hopefully doesn't go to waste.