Clean up logic in conditional control actions

src/cpu/run.rs

@@ -35,6 +35,7 @@ trait Run {
 }
 
 /// `Cycles` represents the number of cycles an operation took
+#[derive(Debug, Copy, Clone)]
 pub struct Cycles(pub u8);
 
 /// `run_instruction` will run the given instruction on the processor.

src/cpu/run/control.rs

@@ -1,6 +1,18 @@
-use crate::cpu::{instructions::control::ControlFlowInstruction, register, Processor};
+use crate::{
+    cpu::{
+        instructions::control::ControlFlowInstruction,
+        register,
+        run::{self, arithutil::CarryingAdd, Cycles, Run},
+        Processor,
+    },
+    register::Flag,
+};
 
-use super::{arithutil::CarryingAdd, Cycles, Run};
+#[derive(Debug, Copy, Clone)]
+struct ConditionalCycles {
+    true_cycles: Cycles,
+    false_cycles: Cycles,
+}
 
 impl Run for ControlFlowInstruction {
     fn run_on(&self, processor: &mut Processor) -> Result<Cycles, super::Error> {
@@ -21,28 +33,30 @@ impl Run for ControlFlowInstruction {
                 Ok(Cycles(4))
             }
 
-            Self::JumpToImmediateIfFlagMatches { flag, value, addr } => {
-                if processor.registers.get_flag_bit(flag) == value {
-                    jump_to(processor, addr);
-                    Ok(Cycles(16))
-                } else {
-                    Ok(Cycles(12))
-                }
-            }
+            Self::JumpToImmediateIfFlagMatches { flag, value, addr } => run_conditional(
+                processor,
+                (flag, value),
+                |action_proc| jump_to(action_proc, addr),
+                ConditionalCycles {
+                    true_cycles: Cycles(16),
+                    false_cycles: Cycles(12),
+                },
+            ),
 
             Self::Call { addr } => {
                 do_call(processor, addr)?;
                 Ok(Cycles(24))
             }
 
-            Self::CallIfFlagMatches { flag, value, addr } => {
-                if processor.registers.get_flag_bit(flag) == value {
-                    do_call(processor, addr)?;
-                    Ok(Cycles(24))
-                } else {
-                    Ok(Cycles(12))
-                }
-            }
+            Self::CallIfFlagMatches { flag, value, addr } => run_fallible_conditional(
+                processor,
+                (flag, value),
+                |action_proc| do_call(action_proc, addr),
+                ConditionalCycles {
+                    true_cycles: Cycles(24),
+                    false_cycles: Cycles(12),
+                },
+            ),
 
             Self::RestartAtAddress { addr } => {
                 let current_pc = processor
@@ -71,14 +85,15 @@ impl Run for ControlFlowInstruction {
                 Ok(Cycles(16))
             }
 
-            Self::ReturnIfFlagMatches { flag, value } => {
-                if processor.registers.get_flag_bit(flag) == value {
-                    return_to_popped_addr(processor)?;
-                    Ok(Cycles(20))
-                } else {
-                    Ok(Cycles(8))
-                }
-            }
+            Self::ReturnIfFlagMatches { flag, value } => run_fallible_conditional(
+                processor,
+                (flag, value),
+                return_to_popped_addr,
+                ConditionalCycles {
+                    true_cycles: Cycles(20),
+                    false_cycles: Cycles(8),
+                },
+            ),
 
             Self::JumpRelative { offset } => {
                 do_relative_jump(processor, offset);
@@ -89,16 +104,50 @@ impl Run for ControlFlowInstruction {
                 flag,
                 value,
                 offset,
-            } => {
-                if processor.registers.get_flag_bit(flag) == value {
-                    do_relative_jump(processor, offset);
-                    Ok(Cycles(12))
+            } => run_conditional(
+                processor,
+                (flag, value),
+                |action_proc| do_relative_jump(action_proc, offset),
+                ConditionalCycles {
+                    true_cycles: Cycles(12),
+                    false_cycles: Cycles(8),
+                },
+            ),
+        }
+    }
+}
+
+fn run_fallible_conditional<F>(
+    processor: &mut Processor,
+    (flag, expected_value): (Flag, u8),
+    true_action: F,
+    cycles: ConditionalCycles,
+) -> Result<Cycles, run::Error>
+where
+    F: Fn(&mut Processor) -> Result<(), run::Error>,
+{
+    if processor.registers.get_flag_bit(flag) == expected_value {
+        true_action(processor).map(|_void| cycles.true_cycles)
     } else {
-                    Ok(Cycles(8))
-                }
-            }
+        Ok(cycles.false_cycles)
     }
 }
+
+fn run_conditional<F>(
+    processor: &mut Processor,
+    flag_conditions: (Flag, u8),
+    true_action: F,
+    cycles: ConditionalCycles,
+) -> Result<Cycles, run::Error>
+where
+    F: Fn(&mut Processor),
+{
+    let succeeding_action = |action_proc: &mut Processor| {
+        true_action(action_proc);
+        Ok(())
+    };
+
+    run_fallible_conditional(processor, flag_conditions, succeeding_action, cycles)
 }
 
 fn do_call(processor: &mut Processor, to_addr: u16) -> Result<(), super::Error> {