Inline assembly

[mahdi259]

Hi
Does anyone know a good source to learn writing inline assembly in C for RISC-V?
My goal is to access memory locations in a C code.
Thanks

[stnolting]

The NEORV32 software framework already provides predefined functions (using inline assembly) for reading/writing from/to arbitrary memory addresses, e.g.:

neorv32/sw/lib/include/neorv32_cpu.h

Lines 159 to 165 in c5dd617

	inline void __attribute__ ((always_inline)) neorv32_cpu_store_unsigned_word(uint32_t addr, uint32_t wdata) {
	uint32_t reg_addr = addr;
	uint32_t reg_data = wdata;
	asm volatile ("sw %[da], 0(%[ad])" : : [da] "r" (reg_data), [ad] "r" (reg_addr));
	}

For a nice RISC-V assembly reference I can recommend the RISC-V Assembly Programmer's Manual: https://github.com/riscv-non-isa/riscv-asm-manual/blob/main/riscv-asm.md

For the C part I would refer to the GCC inline assembly documentation: https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html

[mahdi259]

Thanks a lot. It was very helpful🙏