From 1f88db75f5106eaaef7e0711c226467bbdc9fbb1 Mon Sep 17 00:00:00 2001
From: Marco Thomas <github@marcothms.de>
Date: Wed, 14 May 2025 13:41:08 +0900
Subject: [PATCH] ft: partially implement Group 5 instructions

---
 src/disasm.rs       | 15 ++++++++++++++-
 src/instructions.rs |  3 +++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/disasm.rs b/src/disasm.rs
index 1b3b489..9a53fe6 100644
--- a/src/disasm.rs
+++ b/src/disasm.rs
@@ -613,7 +613,20 @@ impl Disassembler {
                         _ => panic!("Illegal Group 4 mnemonic"),
                     }
                 }
-                0xFF => todo!("Group 5"),
+                0xFF => {
+                    let (target, reg) = self.parse_modrm_byte(Operand::Word(0));
+                    match reg {
+                        0b000 => Mnemonic::INC_Mod(target),
+                        0b001 => Mnemonic::DEC_Mod(target),
+                        0b010 => Mnemonic::CALL_Mod(target),
+                        0b011 => todo!("Implement CALL Mp"),
+                        0b100 => Mnemonic::JMP_Mod(target),
+                        0b101 => todo!("Implement JMP Mp"),
+                        0b110 => Mnemonic::PUSH_Mod(target),
+                        // 0b111 => unused
+                        _ => panic!("Illegal Group 5 mnemonic"),
+                    }
+                }
 
                 _ => {
                     eprintln!("Encountered unknown instruction '0x{:x}'", opcode);
diff --git a/src/instructions.rs b/src/instructions.rs
index 41f6e0f..26e7d83 100644
--- a/src/instructions.rs
+++ b/src/instructions.rs
@@ -77,6 +77,7 @@ pub enum Mnemonic {
     // PUSH
     PUSH_R(Register),
     PUSH_S(SegmentRegister),
+    PUSH_Mod(ModRmTarget),
     // POP
     POP_S(SegmentRegister), // POP to Segment Register
     POP_R(Register),        // POP to Register
@@ -203,10 +204,12 @@ pub enum Mnemonic {
     // CALL
     CALL_p(Pointer),
     CALL_v(Word),
+    CALL_Mod(ModRmTarget),
     // JUMP
     JMP_p(Pointer),
     JMP_b(Byte),
     JMP_v(Word),
+    JMP_Mod(ModRmTarget),
     // WAIT
     WAIT,
     // Push/Pop Flags