relative branches should be shown as $+offset, not just plain offset

while x86 branches of immediates are all relative to PC, other
architectures may have absolute branches to immediate addresses, leaving
this syntax ambiguous and potentially confusing. yaxpeax prefers to
write relative offsets `$+...` as a rule, so uphold that here.

1 files changed, 28 insertions, 0 deletions

diff --git a/src/real_mode/display.rs b/src/real_mode/display.rs
index 9ba8284..f514974 100644
--- a/src/real_mode/display.rs
+++ b/src/real_mode/display.rs
@@ -3351,6 +3351,34 @@ fn contextualize_intel<T: fmt::Write, Y: YaxColors>(instr: &Instruction, colors:
         out.write_str(" ")?;
 
         let x = Operand::from_spec(instr, instr.operands[0]);
+
+        const RELATIVE_BRANCHES: [Opcode; 21] = [
+            Opcode::JMP, Opcode::JCXZ,
+            Opcode::LOOP, Opcode::LOOPZ, Opcode::LOOPNZ,
+            Opcode::JO, Opcode::JNO,
+            Opcode::JB, Opcode::JNB,
+            Opcode::JZ, Opcode::JNZ,
+            Opcode::JNA, Opcode::JA,
+            Opcode::JS, Opcode::JNS,
+            Opcode::JP, Opcode::JNP,
+            Opcode::JL, Opcode::JGE,
+            Opcode::JLE, Opcode::JG,
+        ];
+
+        if instr.operands[0] == OperandSpec::ImmI8 || instr.operands[0] == OperandSpec::ImmI32 {
+            if RELATIVE_BRANCHES.contains(&instr.opcode) {
+                return match x {
+                    Operand::ImmediateI8(rel) => {
+                        write!(out, "$+{}", colors.number(signed_i32_hex(rel as i32)))
+                    }
+                    Operand::ImmediateI32(rel) => {
+                        write!(out, "$+{}", colors.number(signed_i32_hex(rel)))
+                    }
+                    _ => { unreachable!() }
+                };
+            }
+        }
+
         if x.is_memory() {
             out.write_str(MEM_SIZE_STRINGS[instr.mem_size as usize - 1])?;
             out.write_str(" ")?;