applies chatgpt suggestions.

...
does not appear to decode everything

core/src/instruction2/from_bytes.rs

@@ -0,0 +1,23 @@
+use log::debug;
+use crate::address_mode::AddressMode::*;
+use crate::constants::constants_isa_op::*;
+
+fn join_word(low: u8, high: u8) -> u16 {
+    ((high as u16) << 8) | low as u16
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_join_word() {
+        let low: u8 = 0xcd;
+        let high: u8 = 0xab;
+
+        assert_eq!(
+            join_word(low, high),
+            0xabcd
+        );
+    }
+}

core/src/instruction2/mod.rs

@@ -0,0 +1,7 @@
+use crate::address_mode::AddressMode;
+use crate::address_mode::AddressMode::*;
+use crate::mos6502flags::Mos6502Flag::*;
+
+mod from_bytes;
+mod to_bytes;
+mod to_string;

core/src/instruction2/to_bytes.rs

@@ -0,0 +1,38 @@
+use crate::address_mode::AddressMode;
+use crate::address_mode::AddressMode::{Absolute, AbsoluteX, AbsoluteY, Immediate, IndirectX, IndirectY, ZeroPage, ZeroPageX, ZeroPageY};
+use crate::constants::constants_isa_op::*;
+
+fn split_word_hl(to_split: u16) -> (u8, u8) {
+    let low = (to_split & 0xff) as u8;
+    let high = ((to_split & 0xff00) >> 8) as u8;
+    (high, low)
+}
+
+fn split_word_lh(to_split: u16) -> (u8, u8) {
+    let low = (to_split & 0xff) as u8;
+    let high = ((to_split & 0xff00) >> 8) as u8;
+    (low, high)
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn split_le() {
+        let value = 0xabcd;
+        let (high, low) = split_word_hl(value);
+
+        assert_eq!(low, 0xcd);
+        assert_eq!(high, 0xab);
+    }
+
+    #[test]
+    fn split_be() {
+        let value = 0xabcd;
+        let (low, high) = split_word_lh(value);
+
+        assert_eq!(low, 0xcd);
+        assert_eq!(high, 0xab);
+    }
+}

core/src/instruction2/to_string.rs

@@ -0,0 +1,18 @@
+
+fn format(mode: &AddressMode, prefix: &str) -> String {
+    // let suffix = match mode {
+    //     AddressMode::Implied => "",
+    //     AddressMode::Accumulator => " A",
+    //     AddressMode::Immediate(value) => &*format!(" #${value:02x}"),
+    //     AddressMode::ZeroPage(value) => &*format!(" ${value:02x}"),
+    //     AddressMode::ZeroPageX(value) => &*format!(" ${value:02x},X"),
+    //     AddressMode::Absolute(offset) => &*format!(" ${offset:04x}"),
+    //     AddressMode::AbsoluteX(offset) => &*format!(" ${offset:04x},X"),
+    //     AddressMode::AbsoluteY(offset) => &*format!(" ${offset:04x},Y"),
+    //     AddressMode::IndirectX(value) => &*format!(" (${value:02x},X)"),
+    //     AddressMode::IndirectY(value) => &*format!(" (${value:02x}),Y"),
+    //     AddressMode::ZeroPageY(value) => &*format!(" ${value:02x},Y")
+    // };
+    // format!("{}{}", prefix, suffix)
+    prefix.to_string()
+}