fixed a couple of emulator bugs, including fixing shift instructions. finished implementing lib/io/print/print_hex_byte and print_hex_word

.vscode/settings.json

@@ -5,5 +5,5 @@
   "files.eol": "\n",
   "files.insertFinalNewline": true,
   "files.trimFinalNewlines": true,
-  "files.trimTrailingWhitespace": true
+  "files.trimTrailingWhitespace": true,
 }

emulator/src/emulator/system/emulator.rs

@@ -190,7 +190,9 @@ pub fn run_emulator(
                     history.push((addr, instruction));
                 }
                 Err(why) => {
-                    let pcx = processor.get(Register::Pcx);
+                    let pcx = processor
+                        .get(Register::Pcx)
+                        .expect("SPR should never be invalid");
                     report_err(
                         state_tx,
                         &format!(
@@ -211,7 +213,9 @@ pub fn run_emulator(
             let instruction = match processor.cycle() {
                 Ok(instruction) => instruction,
                 Err(why) => {
-                    let pcx = processor.get(Register::Pcx);
+                    let pcx = processor
+                        .get(Register::Pcx)
+                        .expect("PCX should never be invalid");
                     report_err(
                         state_tx,
                         &format!(

emulator/src/emulator/system/model.rs

@@ -257,8 +257,8 @@ impl RegFile {
         self.pcx = 0;
     }
 
-    pub fn reg(&mut self, reg: Register) -> &mut u32 {
+    pub const fn reg(&mut self, reg: Register) -> Result<&mut u32, ProcessorError> {
-        match reg {
+        Ok(match reg {
             Register::Rg0 => &mut self.rg0,
             Register::Rg1 => &mut self.rg1,
             Register::Rg2 => &mut self.rg2,
@@ -286,13 +286,13 @@ impl RegFile {
             Register::Sts => &mut self.sts,
             Register::Cir => &mut self.cir,
             Register::Pcx => &mut self.pcx,
-            _ => panic!("Invalid register."),
+            _ => return Err(ProcessorError::InvalidRegister(Register::NoReg as u8)),
-        }
+        })
     }
 
     #[must_use]
-    pub fn get(&self, reg: Register) -> u32 {
+    pub const fn get(&self, reg: Register) -> Result<u32, ProcessorError> {
-        match reg {
+        Ok(match reg {
             Register::Rg0 => self.rg0,
             Register::Rg1 => self.rg1,
             Register::Rg2 => self.rg2,
@@ -321,7 +321,7 @@ impl RegFile {
             Register::Cir => self.cir,
             Register::Pcx => self.pcx,
             Register::Zero => 0,
-            _ => panic!("Invalid register."),
+            _ => return Err(ProcessorError::InvalidRegister(Register::NoReg as u8)),
-        }
+        })
     }
 }

emulator/src/emulator/system/processor/mod.rs

@@ -16,7 +16,7 @@ pub struct Processor {
     pub halted: bool,
     pub io_devices: Vec<Arc<dyn IODevice>>,
 
-    pub dustbin: u32,
+    pub void: u32,
 }
 
 fn log(message: &str) {
@@ -31,7 +31,7 @@ impl Processor {
             registers: RegFile::default(),
             halted: false,
             io_devices,
-            dustbin: 0,
+            void: 0,
         }
     }
 
@@ -49,16 +49,16 @@ impl Processor {
         self.halted = false;
 
         // Get value from PCX.
-        let addr = self.fetch();
+        let addr = self.fetch()?;
         // Increment PCX.
         self.advance();
 
         // Set MAR to the previous value of PCX.
-        *self.reg(Register::Mar) = addr;
+        *self.reg(Register::Mar)? = addr;
         let val = self.memory.read_word(addr)?;
 
         // Set CIR to the value of RAM[MAR].
-        *self.reg(Register::Mar) = val;
+        *self.reg(Register::Mar)? = val;
 
         // Decode and execute the instruction.
         let instruction = Instruction::decode(val)
@@ -68,18 +68,17 @@ impl Processor {
         Ok((addr, instruction))
     }
 
-    fn fetch(&self) -> u32 {
+    const fn fetch(&self) -> Result<u32, ProcessorError> {
         self.get(Register::Pcx)
     }
 
-    #[must_use]
+    pub const fn get(&self, reg: Register) -> Result<u32, ProcessorError> {
-    pub fn get(&self, reg: Register) -> u32 {
         self.registers.get(reg)
     }
 
-    pub fn reg(&mut self, reg: Register) -> &mut u32 {
+    pub const fn reg(&mut self, reg: Register) -> Result<&mut u32, ProcessorError> {
         match reg {
-            Register::Zero => &mut self.dustbin,
+            Register::Zero => Ok(&mut self.void),
             _ => self.registers.reg(reg),
         }
     }
@@ -97,51 +96,57 @@ impl Processor {
     // functions to set new state
     fn set_flag(&mut self, flag: Flag, value: bool) {
         if value {
-            *self.reg(Register::Sts) |= flag as u32;
+            *self
+                .reg(Register::Sts)
+                .expect("STS should never be invalid") |= flag as u32;
         } else {
-            *self.reg(Register::Sts) &= !(flag as u32);
+            *self
+                .reg(Register::Sts)
+                .expect("STS should never be invalid") &= !(flag as u32);
         }
     }
 
-    fn get_flag(&self, flag: Flag) -> bool {
+    fn get_flag(&self, flag: Flag) -> Result<bool, ProcessorError> {
-        self.get(Register::Sts) & (flag as u32) != 0
+        Ok(self.get(Register::Sts)? & (flag as u32) != 0)
     }
 
-    fn advance(&mut self) {
+    fn advance(&mut self) -> Result<(), ProcessorError> {
         // increment PCX
-        *self.reg(Register::Pcx) += 4;
+        *self.reg(Register::Pcx)? += 4;
+        Ok(())
     }
 
-    fn jump(&mut self, reg: Register, offset: u16) {
+    fn jump(&mut self, reg: Register, offset: u16) -> Result<(), ProcessorError> {
-        *self.reg(Register::Pcx) = self.get(reg) + u32::from(offset);
+        *self.reg(Register::Pcx)? = self.get(reg)? + u32::from(offset);
+        Ok(())
     }
 
     pub fn begin_interrupt(
         &mut self,
         interrupt: Interrupt,
     ) -> Result<(), ProcessorError> {
-        let idt = self.get(Register::Idr);
+        let idt = self.get(Register::Idr)?;
 
         let addr = self
             .memory
             .read_word(idt + u32::from(interrupt.as_u8()) * 4)?;
         println!("INFO: Interrupt {interrupt:?} addr: {addr}");
 
-        self.push(self.get(Register::Pcx))?;
+        self.push(self.get(Register::Pcx)?)?;
-        *self.reg(Register::Pcx) = addr;
+        *self.reg(Register::Pcx)? = addr;
         Ok(())
     }
 
     fn push(&mut self, val: u32) -> Result<(), ProcessorError> {
-        *self.reg(Register::Spr) -= 4;
+        *self.reg(Register::Spr)? -= 4;
-        let reg = *self.reg(Register::Spr);
+        let reg = *self.reg(Register::Spr)?;
         self.memory.write_word(reg, val)
     }
 
     fn pop(&mut self) -> Result<u32, ProcessorError> {
-        let reg = *self.reg(Register::Spr);
+        let reg = *self.reg(Register::Spr)?;
         let val = self.memory.read_word(reg)?;
-        *self.reg(Register::Spr) += 4;
+        *self.reg(Register::Spr)? += 4;
         Ok(val)
     }
 
@@ -149,13 +154,13 @@ impl Processor {
     #[allow(clippy::needless_pass_by_ref_mut)]
     fn end_interrupt(&mut self) -> Result<(), ProcessorError> {
         let ret = self.pop()?;
-        *self.reg(Register::Ret) = ret;
+        *self.reg(Register::Ret)? = ret;
-        *self.reg(Register::Pcx) = ret;
+        *self.reg(Register::Pcx)? = ret;
         Ok(())
     }
 
     pub fn get_stack(&mut self, n: u32) -> Result<Vec<u8>, ProcessorError> {
-        let addr = self.get(Register::Spr);
+        let addr = self.get(Register::Spr)?;
         let size = n * 4;
         // returns the stack
         self.memory.read_range(
@@ -190,30 +195,30 @@ impl Executable for Instruction {
             // No operation - a blank line.
             // Copies from SrcReg to a.drReg.
             Self::Mov(a) => {
-                *cpu.reg(a.dr) = cpu.get(a.sr1);
+                *cpu.reg(a.dr)? = cpu.get(a.sr1)?;
             }
 
             // Copies from SrcReg to a.drReg, sign extending the value to take up a full
             // word.
             Self::MovSigned(a) => {
-                *cpu.reg(a.dr) = sign_extend(cpu.get(a.sr1));
+                *cpu.reg(a.dr)? = sign_extend(cpu.get(a.sr1)?);
             }
 
             // Loads a byte from memory address (base + offset) into a.drReg. The
             // effective address must be byte-aligned.
             Self::LoadByte(a) => {
-                *cpu.reg(a.r2) = u32::from(
+                *cpu.reg(a.r2)? = u32::from(
                     cpu.memory
-                        .read_byte(cpu.get(a.r1) + u32::from(a.immediate))?,
+                        .read_byte(cpu.get(a.r1)? + u32::from(a.immediate))?,
                 );
             }
 
             // Loads a sign-extended byte from memory address (base + offset) into
             // a.drReg. The effective address must be byte-aligned.
             Self::LoadByteSigned(a) => {
-                *cpu.reg(a.r2) = sign_extend(u32::from(
+                *cpu.reg(a.r2)? = sign_extend(u32::from(
                     cpu.memory
-                        .read_byte(cpu.get(a.r1) + u32::from(a.immediate))?,
+                        .read_byte(cpu.get(a.r1)? + u32::from(a.immediate))?,
                 ));
             }
 
@@ -222,18 +227,18 @@ impl Executable for Instruction {
             Self::LoadHalfword(a) => {
                 // we read an entire word, then right shift so we only get the first half
                 // of the word
-                *cpu.reg(a.r2) = cpu
+                *cpu.reg(a.r2)? = cpu
                     .memory
-                    .read_word(cpu.get(a.r1) + u32::from(a.immediate))?
+                    .read_word(cpu.get(a.r1)? + u32::from(a.immediate))?
                     >> 16;
             }
 
             // Loads a sign-extended half-word from memory address (base + offset) into
             // a.drReg. The effective address must be 2-byte-aligned.
             Self::LoadHalfwordSigned(a) => {
-                *cpu.reg(a.r2) = sign_extend(
+                *cpu.reg(a.r2)? = sign_extend(
                     cpu.memory
-                        .read_word(cpu.get(a.r1) + u32::from(a.immediate))?
+                        .read_word(cpu.get(a.r1)? + u32::from(a.immediate))?
                         >> 16,
                 );
             }
@@ -241,17 +246,17 @@ impl Executable for Instruction {
             // Loads a word from memory address (base + offset) into a.drReg. The
             // effective address must be 4-byte-aligned.
             Self::LoadWord(a) => {
-                *cpu.reg(a.r2) = cpu
+                *cpu.reg(a.r2)? = cpu
                     .memory
-                    .read_word(cpu.get(a.r1) + u32::from(a.immediate))?;
+                    .read_word(cpu.get(a.r1)? + u32::from(a.immediate))?;
             }
 
             // Stores a byte from SrcReg in memory address (base + offset) The effective
             // address must be byte-aligned.
             Self::StoreByte(a) => {
                 cpu.memory.write_byte(
-                    cpu.get(a.r2) + u32::from(a.immediate),
+                    cpu.get(a.r2)? + u32::from(a.immediate),
-                    cpu.get(a.r1) as u8,
+                    cpu.get(a.r1)? as u8,
                 )?;
             }
 
@@ -259,149 +264,147 @@ impl Executable for Instruction {
             // effective address must be 2-byte-aligned.
             Self::StoreHalfword(a) => {
                 // split the value into bytes and then write two bytes
-                let bytes = (cpu.get(a.r1) as u16).to_le_bytes();
+                let bytes = (cpu.get(a.r1)? as u16).to_le_bytes();
                 cpu.memory
-                    .write_byte(cpu.get(a.r2) + u32::from(a.immediate), bytes[0])?;
+                    .write_byte(cpu.get(a.r2)? + u32::from(a.immediate), bytes[0])?;
                 cpu.memory
-                    .write_byte(cpu.get(a.r2) + u32::from(a.immediate) + 1, bytes[1])?;
+                    .write_byte(cpu.get(a.r2)? + u32::from(a.immediate) + 1, bytes[1])?;
             }
 
             // Stores a word from SrcReg in memory address (base + offset) The effective
             // address must be 4-byte-aligned.
             Self::StoreWord(a) => {
-                cpu.memory
+                cpu.memory.write_word(
-                    .write_word(cpu.get(a.r2) + u32::from(a.immediate), cpu.get(a.r1))?;
+                    cpu.get(a.r2)? + u32::from(a.immediate),
+                    cpu.get(a.r1)?,
+                )?;
             }
 
             // Loads a 16-bit literal value into reg, setting the bottom 16 bits of the
             // word. To populate the upper 16 bits, see LUI.
             Self::LoadLowerImmediate(a) => {
-                *cpu.reg(a.r1) = u32::from(a.immediate);
+                *cpu.reg(a.r1)? = u32::from(a.immediate);
             }
 
             // Loads a 16-bit literal value into reg, setting the top 16 bits of the word.
             // To populate the lower 16 bits, see LLI.
             Self::LoadUpperImmediate(a) => {
-                *cpu.reg(a.r1) =
+                *cpu.reg(a.r1)? =
-                    (cpu.get(a.r1) & 0x0000_FFFF) | (u32::from(a.immediate) << 16);
+                    (cpu.get(a.r1)? & 0x0000_FFFF) | (u32::from(a.immediate) << 16);
             }
 
             // Unconditionally jumps to the calculated address or direct address
-            Self::Jump(a) => cpu.jump(a.r1, a.immediate),
+            Self::Jump(a) => cpu.jump(a.r1, a.immediate)?,
 
             // Jumps to the calculated address or direct address if equal flag set.
             Self::JumpEq(a) => {
-                if cpu.get_flag(Flag::Equal) {
+                if cpu.get_flag(Flag::Equal)? {
-                    cpu.jump(a.r1, a.immediate);
+                    cpu.jump(a.r1, a.immediate)?;
                 }
             }
 
             // Jumps to the calculated address or direct address if equal flag not set.
             Self::JumpNeq(a) => {
-                if !cpu.get_flag(Flag::Equal) {
+                if !cpu.get_flag(Flag::Equal)? {
-                    cpu.jump(a.r1, a.immediate);
+                    cpu.jump(a.r1, a.immediate)?;
                 }
             }
 
             // Jumps to the calculated address or direct address if greater than flag set.
             Self::JumpGt(a) => {
-                if cpu.get_flag(Flag::GreaterThan) {
+                if cpu.get_flag(Flag::GreaterThan)? {
-                    cpu.jump(a.r1, a.immediate);
+                    cpu.jump(a.r1, a.immediate)?;
                 }
             }
 
             // Jumps to the calculated address or direct address if greater than flag or
             // equal flag set.
             Self::JumpGe(a) => {
-                if cpu.get_flag(Flag::GreaterThan) || cpu.get_flag(Flag::Equal) {
+                if cpu.get_flag(Flag::GreaterThan)? || cpu.get_flag(Flag::Equal)? {
-                    cpu.jump(a.r1, a.immediate);
+                    cpu.jump(a.r1, a.immediate)?;
                 }
             }
 
             // Jumps to the calculated address or direct address if less than flag set.
             Self::JumpLt(a) => {
-                if cpu.get_flag(Flag::LessThan) {
+                if cpu.get_flag(Flag::LessThan)? {
-                    cpu.jump(a.r1, a.immediate);
+                    cpu.jump(a.r1, a.immediate)?;
                 }
             }
 
             // Jumps to the calculated address or direct address if less than flag or
             // equal flag set.
             Self::JumpLe(a) => {
-                if cpu.get_flag(Flag::LessThan) || cpu.get_flag(Flag::Equal) {
+                if cpu.get_flag(Flag::LessThan)? || cpu.get_flag(Flag::Equal)? {
-                    cpu.jump(a.r1, a.immediate);
+                    cpu.jump(a.r1, a.immediate)?;
                 }
             }
 
             // Increments the value in the given register
-            Self::Increment(a) => *cpu.reg(a.sr1) = inc(cpu.get(a.sr1)),
+            Self::Increment(a) => *cpu.reg(a.sr1)? = inc(cpu.get(a.sr1)?),
 
             // Decrements the value in the given register
-            Self::Decrement(a) => *cpu.reg(a.sr1) = dec(cpu.get(a.sr1)),
+            Self::Decrement(a) => *cpu.reg(a.sr1)? = dec(cpu.get(a.sr1)?),
 
             // Left shifts the value in Reg by the given amount (either a register, or a
             // literal value)
             Self::ShiftLeft(a) => {
-                let regval = cpu.get(a.sr2);
+                let reg = cpu.get(a.sr1)?;
-                let val = cpu.get(a.sr1);
+                let val = a.shamt;
-
+                *cpu.reg(a.sr1)? = shl(reg, val);
-                *cpu.reg(a.sr1) =
-                    shl(val, if regval != 0 { regval as u8 } else { a.shamt });
             }
 
             // Right shifts the value in Reg by the given amount (either a register, or a
             // literal value).
             Self::ShiftRight(a) => {
-                let regval = cpu.get(a.sr2);
+                let regval = cpu.get(a.sr1)?;
-                let val = cpu.get(a.sr1);
+                let val = a.shamt;
-
+                *cpu.reg(a.sr1)? = shr(regval, val);
-                *cpu.reg(a.sr1) =
-                    shr(val, if regval != 0 { regval as u8 } else { a.shamt });
             }
 
             // Adds the value of Src2 to Src1 and writes the result to a.dr
             Self::Add(a) => {
-                *cpu.reg(a.dr) = add(cpu.get(a.sr1), cpu.get(a.sr2));
+                *cpu.reg(a.dr)? = add(cpu.get(a.sr1)?, cpu.get(a.sr2)?);
             }
 
             // Subtracts the value of Src2 from Src1 and writes the result to a.dr
             Self::Sub(a) => {
-                *cpu.reg(a.dr) = sub(cpu.get(a.sr1), cpu.get(a.sr2));
+                *cpu.reg(a.dr)? = sub(cpu.get(a.sr1)?, cpu.get(a.sr2)?);
             }
 
             Self::AddImmediate(a) => {
-                *cpu.reg(a.r2) = add(cpu.get(a.r1), u32::from(a.immediate));
+                *cpu.reg(a.r2)? = add(cpu.get(a.r1)?, u32::from(a.immediate));
             }
 
             Self::SubImmediate(a) => {
-                *cpu.reg(a.r2) = sub(cpu.get(a.r1), u32::from(a.immediate));
+                *cpu.reg(a.r2)? = sub(cpu.get(a.r1)?, u32::from(a.immediate));
             }
 
             // Performs bitwise AND on Src1 and Src2 storing the result in a.dr
-            Self::And(a) => *cpu.reg(a.dr) = and(cpu.get(a.sr1), cpu.get(a.sr2)),
+            Self::And(a) => *cpu.reg(a.dr)? = and(cpu.get(a.sr1)?, cpu.get(a.sr2)?),
 
             // Performs bitwise OR on Src1 and Src2 storing the result in a.dr
-            Self::Or(a) => *cpu.reg(a.dr) = or(cpu.get(a.sr1), cpu.get(a.sr2)),
+            Self::Or(a) => *cpu.reg(a.dr)? = or(cpu.get(a.sr1)?, cpu.get(a.sr2)?),
 
             // Performs bitwise NOT on Src storing the result in a.dr
-            Self::Not(a) => *cpu.reg(a.dr) = not(cpu.get(a.sr1)),
+            Self::Not(a) => *cpu.reg(a.dr)? = not(cpu.get(a.sr1)?),
 
             // Performs bitwise XOR on Src1 and Src2 storing the result in a.dr
-            Self::Xor(a) => *cpu.reg(a.dr) = xor(cpu.get(a.sr1), cpu.get(a.sr2)),
+            Self::Xor(a) => *cpu.reg(a.dr)? = xor(cpu.get(a.sr1)?, cpu.get(a.sr2)?),
 
             // Performs bitwise NAND on Src1 and Src2 storing the result in a.dr
-            Self::Nand(a) => *cpu.reg(a.dr) = nand(cpu.get(a.sr1), cpu.get(a.sr2)),
+            Self::Nand(a) => *cpu.reg(a.dr)? = nand(cpu.get(a.sr1)?, cpu.get(a.sr2)?),
 
             // Performs bitwise NOR on Src1 and Src2 storing the result in a.dr
-            Self::Nor(a) => *cpu.reg(a.dr) = nor(cpu.get(a.sr1), cpu.get(a.sr2)),
+            Self::Nor(a) => *cpu.reg(a.dr)? = nor(cpu.get(a.sr1)?, cpu.get(a.sr2)?),
 
             // Performs bitwise XNOR on Src1 and Src2 storing the result in a.dr
-            Self::Xnor(a) => *cpu.reg(a.dr) = xnor(cpu.get(a.sr1), cpu.get(a.sr2)),
+            Self::Xnor(a) => *cpu.reg(a.dr)? = xnor(cpu.get(a.sr1)?, cpu.get(a.sr2)?),
 
             // Compares the value of Reg1 to the value in Reg2. The results of the
             // comparisons are set in the Status register.
             Self::Compare(a) => {
-                cpu.cmp(cpu.get(a.sr1), cpu.get(a.sr2));
+                cpu.cmp(cpu.get(a.sr1)?, cpu.get(a.sr2)?);
             }
 
             // Initiates an interrupt with the given 8 bit interrupt code.

emulator/src/emulator/ui/control_unit.rs

@@ -133,17 +133,25 @@ impl Component for ControlPanel {
                 }
             ));
 
-            let pcx = state.reg_file.get(Register::Pcx);
+            let pcx = state
+                .reg_file
+                .get(Register::Pcx)
+                .expect("PCX should never be invalid");
             let instructions = state.instructions;
 
             ui.label(format!("Instructions: {instructions}"));
             ui.label(format!("PC: 0x{pcx:08X}"));
 
-            let instruction = Instruction::decode(state.reg_file.get(Register::Cir))
+            let instruction = Instruction::decode(
-                .map_or_else(
+                state
-                    |_| "Invalid Instruction".to_string(),
+                    .reg_file
-                    |instruction| instruction.to_string(),
+                    .get(Register::Cir)
-                );
+                    .expect("CIR should never be invalid"),
+            )
+            .map_or_else(
+                |_| "Invalid Instruction".to_string(),
+                |instruction| instruction.to_string(),
+            );
 
             ui.label(format!("Instruction: {instruction}"));
         });

emulator/src/emulator/ui/stack_inspector.rs

@@ -61,7 +61,7 @@ impl Component for StackInspector {
                                 ui.label(format!(
                                     "{} [{}]",
                                     i,
-                                    state.reg_file.get(Register::Spr) - i as u32 * 4
+                                    state.reg_file.get(Register::Spr).expect("SPR should never be invalid") - i as u32 * 4
                                 ));
                                 ui.label(format!("0x{value:08X} ({value})"));
                                 ui.end_row();

resources/dsa/lib/io/print.dsa

@@ -82,14 +82,48 @@ print_byte:
 
 // ------------------------------------------
 // prints the value of arg[0] to the screen in hex.
+print_hex_word:
+    push bpr
+    mov spr, bpr
+
+    ldw current, rg1
+
+    ldb bpr, rg0, 8
+    push rg0
+    call _print_hex_byte
+    addi spr, 4
+
+    ldb bpr, rg0, 9
+    push rg0
+    call _print_hex_byte
+    addi spr, 4
+
+    ldb bpr, rg0, 10
+    push rg0
+    call _print_hex_byte
+    addi spr, 4
+
+    ldb bpr, rg0, 11
+    push rg0
+    call _print_hex_byte
+    addi spr, 4
+
+    jmp _end
+
+// ------------------------------------------
+// prints the last byte of arg[0] to the screen in hex.
 print_hex_byte:
     push bpr
     mov spr, bpr
 
-    // put arg byte in rg0
     ldw bpr, rg0, 8
     ldw current, rg1
 
+    call _print_hex_byte
+    jmp _end
+
+// function body
+_print_hex_byte:
     // mask to get lower nibble
     lli 0xF, rg2
     // save rg0 state
@@ -102,8 +136,9 @@ print_hex_byte:
 
     and rg0, rg2, rg0
     call _print_hex_nibble
-    jmp _end
+    return
 
+// print a hex digit
 _print_hex_nibble:
     lli 10, rg3
     cmp rg0, rg3
@@ -111,26 +146,14 @@ _print_hex_nibble:
     addi rg0, 0x37, rg0
     stb rg0, rg1
     addi rg1, 1
-    jmp _end
+    return
 
+// helper function.
 _print_hex_nibble_number:
     addi rg0, 0x30, rg0
     stb rg0, rg1
     addi rg1, 1
-    jmp _end
+    return
-
-// ------------------------------------------
-// prints the value of arg[0] to the screen in hex.
-print_hex_word:
-    push bpr
-    mov spr, bpr
-
-    ldw bpr, rg0, 8
-    ldw current, rg1
-
-    stw rg0, rg1
-    addi rg1, 4
-    jmp _end
 
 // ------------------------------------------
 // resets the cursor position on the screen to 0x20000. (0,0)

resources/dsa/test.dsa

@@ -16,9 +16,9 @@ start:
 	stw rg0, idr, 4
 
 	
-	lli 0x20, rg0
+	lwi 0x1234abcd, rg0
 	push rg0
-	call print::print_hex_byte
+	call print::print_hex_word
 	pop zero
 	hlt