Hello, I was trying to write one byte to an I/O port, but I am failing finding the correct instructions in the instruction set of arm64 aarch64 architecture. I failed to find the answer in previous posts of this forum too.
To be sure I posted the question correctly, please consider a NS16550 uart.
NS16550
I want, basically, to use `outb` (or `inb`) instructions, but I do not find the correct syntax. An equivalent example in i386 is:
Fullscreen123456789void dbg_io_write_8(uint16_t port, uint8_t val){ asm volatile ( "outb %%al, %%dx;" /* Outputs */ : /* None */ /* Inputs */ : "a" (val), "d" (port) /* Clobbers */ : /* None */ );}XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXvoid dbg_io_write_8(uint16_t port, uint8_t val) { asm volatile ( "outb %%al, %%dx;" /* Outputs */ : /* None */ /* Inputs */ : "a" (val), "d" (port) /* Clobbers */ : /* None */ ); }
void dbg_io_write_8(uint16_t port, uint8_t val) { asm volatile ( "outb %%al, %%dx;" /* Outputs */ : /* None */ /* Inputs */ : "a" (val), "d" (port) /* Clobbers */ : /* None */ ); }
And, the equivalent for reading:
Fullscreen12345678910111213uint8_t dbg_io_read_8(uint16_t port){ uint8_t val; asm volatile ( "inb %%dx, %%al;" /* Outputs */ : "=a" (val) /* Inputs */ : "d" (port) /* Clobbers */ : /* None */ ); return val;}XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXuint8_t dbg_io_read_8(uint16_t port) { uint8_t val; asm volatile ( "inb %%dx, %%al;" /* Outputs */ : "=a" (val) /* Inputs */ : "d" (port) /* Clobbers */ : /* None */ ); return val; }Thanks for helping!
uint8_t dbg_io_read_8(uint16_t port) { uint8_t val; asm volatile ( "inb %%dx, %%al;" /* Outputs */ : "=a" (val) /* Inputs */ : "d" (port) /* Clobbers */ : /* None */ ); return val; }