branching instructions

that's all of the 8080 instruction set besides the I/O instructions

god bless

src/emulator/instructions/branch.rs

@@ -0,0 +1,52 @@
+use crate::transfer::{pop, push};
+use crate::{get_register_pair, EmulatorState, Register};
+
+/// Jump (set PC) to specified address
+pub fn jump(address: u16, state: &mut EmulatorState) {
+    state.pc = address;
+}
+
+/// Jump to a specified address only if `cond` is true
+pub fn jump_cond(address: u16, cond: bool, state: &mut EmulatorState) {
+    if cond {
+        jump(address, state);
+    }
+}
+
+/// Push the current PC to the stack and jump to the specified address
+pub fn call(address: u16, state: &mut EmulatorState) {
+    push(state.pc, state);
+    jump(address, state);
+}
+
+// Push the current PC to the stack and jump to the specified address if `cond` is true
+pub fn call_cond(address: u16, cond: bool, state: &mut EmulatorState) {
+    if cond {
+        call(address, state);
+    }
+}
+
+// Pop a value from the stack and jump to it
+pub fn ret(state: &mut EmulatorState) {
+    jump(pop(state), state);
+}
+
+// Pop a value from the stack and jump to it if `cond` is true
+pub fn ret_cond(cond: bool, state: &mut EmulatorState) {
+    if cond {
+        ret(state)
+    }
+}
+
+/// "Restart" at (call) a specific interrupt vector
+///
+/// Panics if `vector` is 8 or above
+pub fn restart(vector: u8, state: &mut EmulatorState) {
+    assert!(vector < 8, "Illegal restart vector");
+    call((vector * 8) as u16, state);
+}
+
+/// Load a new program counter from the HL register pair
+pub fn pchl(state: &mut EmulatorState) {
+    state.pc = get_register_pair(Register::H, state);
+}

src/emulator/instructions/mod.rs

@@ -1,2 +1,3 @@
 pub mod arithmetic;
+pub mod branch;
 pub mod transfer;

src/emulator/instructions/transfer.rs

@@ -1,6 +1,5 @@
 use crate::{
-    get_register, get_register_pair, set_register, structs::set_register_pair, EmulatorState,
-    Register,
+    get_register, get_register_pair, set_register, set_register_pair, EmulatorState, Register,
 };
 
 /// Move (copy) value from source to destination register

src/emulator/main.rs

@@ -1,4 +1,4 @@
-use instructions::{arithmetic, transfer};
+use instructions::{arithmetic, branch, transfer};
 use std::{env, fs};
 
 use crate::structs::*;
@@ -164,6 +164,53 @@ fn tick(state: &mut EmulatorState) {
         0xf6 => arithmetic::or(state.next_byte(), state),                                // ORI
         0xfe => arithmetic::cmp(state.next_byte(), state),                               // CPI
 
+        /* Branch instructions */
+        // Jumps
+        0xc2 => branch::jump_cond(state.next_word(), !state.cc.z, state), // JNZ
+        0xc3 => branch::jump(state.next_word(), state),                   // JMP
+        0xca => branch::jump_cond(state.next_word(), state.cc.z, state),  // JZ
+        0xd2 => branch::jump_cond(state.next_word(), !state.cc.c, state), // JNC
+        0xda => branch::jump_cond(state.next_word(), state.cc.c, state),  // JC
+        0xe2 => branch::jump_cond(state.next_word(), !state.cc.p, state), // JPO
+        0xea => branch::jump_cond(state.next_word(), state.cc.p, state),  // JPE
+        0xf2 => branch::jump_cond(state.next_word(), !state.cc.s, state), // JP
+        0xfa => branch::jump_cond(state.next_word(), state.cc.s, state),  // JM
+
+        // Calls
+        0xc4 => branch::call_cond(state.next_word(), !state.cc.z, state), // CNZ
+        0xcc => branch::call_cond(state.next_word(), state.cc.z, state),  // CZ
+        0xcd => branch::call(state.next_word(), state),                   // CALL
+        0xd4 => branch::call_cond(state.next_word(), !state.cc.c, state), // CNC
+        0xdc => branch::call_cond(state.next_word(), state.cc.c, state),  // CC
+        0xe4 => branch::call_cond(state.next_word(), !state.cc.p, state), // CPO
+        0xec => branch::call_cond(state.next_word(), state.cc.p, state),  // CPE
+        0xf4 => branch::call_cond(state.next_word(), !state.cc.s, state), // CP
+        0xfc => branch::call_cond(state.next_word(), state.cc.s, state),  // CM
+
+        // Returns
+        0xc0 => branch::ret_cond(!state.cc.z, state), // RNZ
+        0xc8 => branch::ret_cond(state.cc.z, state),  // RZ
+        0xc9 => branch::ret(state),                   // RET
+        0xd0 => branch::ret_cond(!state.cc.c, state), // RNC
+        0xd8 => branch::ret_cond(state.cc.c, state),  // RC
+        0xe0 => branch::ret_cond(!state.cc.p, state), // RPO
+        0xe8 => branch::ret_cond(state.cc.p, state),  // RPE
+        0xf0 => branch::ret_cond(!state.cc.s, state), // RP
+        0xf8 => branch::ret_cond(state.cc.s, state),  // RM
+
+        // Restarts
+        0xc7 => branch::restart(0, state),
+        0xcf => branch::restart(1, state),
+        0xd7 => branch::restart(2, state),
+        0xdf => branch::restart(3, state),
+        0xe7 => branch::restart(4, state),
+        0xef => branch::restart(5, state),
+        0xf7 => branch::restart(6, state),
+        0xff => branch::restart(7, state),
+
+        // PCHL
+        0xe9 => branch::pchl(state),
+
         _ => not_implemented(state),
     }