Cosmos/source/Cosmos.Core.DebugStub/SerialIO.xs

namespace DebugStub

// handles the reading and writing to serial (16550A) registers

// optionally exclude this serial version


! %ifndef Exclude_IOPort_Based_Serial

// mComPortAddresses = 0x3F8, 0x2F8, 0x3E8, 0x2E8;
// Currently hardcoded to COM1.
var ComAddr = $03F8

// writes to a UART register
// uses:
//    DX -> Port offset
//    AL -> value to write
// Modifies:
//    DX

function WriteRegister {
  +EDX
    DX + $03F8
    Port[DX] = AL
  -EDX
}

// reads from a UART register
// uses:
//    DX -> Port offset
// Modifies:
//    AL -> value read
function ReadRegister {
  +EDX
    DX + $03F8
    AL = Port[DX]
  -EDX
}

! %endif