feat(cmd): add gasm dis and share the decoder with the debugger

debug/disasm_linux_amd64.go

@@ -9,27 +9,22 @@ import (
 	"fmt"
 	"strings"
 
-	"golang.org/x/arch/x86/x86asm"
+	"sourcedock.dev/petrbalvin/gasm-devkit/arch"
+	"sourcedock.dev/petrbalvin/gasm-devkit/disasm"
 )
 
 // Disassemble decodes the instruction at the given address in the debuggee's
 // memory and returns its text representation and length in bytes.
 func (s *Session) Disassemble(addr uint64) (string, int, error) {
-	// Read up to 15 bytes (max x86 instruction length).
 	mem, err := s.ReadMemory(addr, 15)
 	if err != nil {
-		// Try a shorter read if we're near a page boundary.
-		mem, err = s.ReadMemory(addr, 1)
-		if err != nil {
-			return "", 0, err
-		}
+		return "", 0, err
 	}
-	inst, err := x86asm.Decode(mem, 64)
+	ins, err := disasm.Decode(arch.AMD64, mem, addr)
 	if err != nil {
-		return "???", 1, nil
+		return "", 0, err
 	}
-	text := x86asm.IntelSyntax(inst, addr, nil)
-	return text, inst.Len, nil
+	return ins.Text, ins.Len, nil
 }
 
 // DisassembleN decodes up to n instructions starting at addr and returns