Pull out memory access instructions from rvi.rs to their own file

src/instructions/rvi/mem.rs

@@ -0,0 +1,117 @@
+use crate::{
+    consts::{Addr, Byte, DWord, Word},
+    core::Core,
+    instructions::{Instruction, InstructionResult},
+    mem::PageNum,
+};
+
+// TODO: Support misaligned memory access
+pub fn sd(core: &mut Core, instr: Instruction) -> InstructionResult {
+    let addr = core.reg_read(instr.rs1()).wrapping_add(instr.imm_s());
+
+    if !addr.is_multiple_of(std::mem::size_of::<DWord>() as Addr) {
+        return InstructionResult::Exception(());
+    }
+
+    let page = (addr / 4096) as PageNum;
+    let offset = (addr / 8 & ((4096 / 8 as Addr) - 1)) as u16;
+    let value = core.reg_read(instr.rs2());
+
+    match core.mem.write_dword(page, offset, value) {
+        Ok(_) => {
+            core.advance_pc();
+            InstructionResult::Normal
+        }
+        Err(_) => InstructionResult::Exception(()),
+    }
+}
+
+pub fn ld(core: &mut Core, instr: Instruction) -> InstructionResult {
+    let addr = core.reg_read(instr.rs1()).wrapping_add(instr.imm_i());
+
+    if !addr.is_multiple_of(std::mem::size_of::<DWord>() as Addr) {
+        return InstructionResult::Exception(());
+    }
+
+    let page = (addr / 4096) as PageNum;
+    let offset = (addr / 8 & ((4096 / 8 as Addr) - 1)) as u16;
+
+    match core.mem.read_dword(page, offset) {
+        Ok(x) => {
+            core.reg_write(instr.rd(), x);
+            core.advance_pc();
+            InstructionResult::Normal
+        }
+        Err(_) => InstructionResult::Exception(()),
+    }
+}
+
+pub fn sw(core: &mut Core, instr: Instruction) -> InstructionResult {
+    let addr = core.reg_read(instr.rs1()).wrapping_add(instr.imm_s());
+
+    if !addr.is_multiple_of(std::mem::size_of::<Word>() as Addr) {
+        return InstructionResult::Exception(());
+    }
+
+    let page = (addr / 4096) as PageNum;
+    let offset = (addr / 4 & ((4096 / 4 as Addr) - 1)) as u16;
+    let value = core.reg_read(instr.rs2()) as Word;
+
+    match core.mem.write_word(page, offset, value) {
+        Ok(_) => {
+            core.advance_pc();
+            InstructionResult::Normal
+        }
+        Err(_) => InstructionResult::Exception(()),
+    }
+}
+
+pub fn sb(core: &mut Core, instr: Instruction) -> InstructionResult {
+    let addr = core.reg_read(instr.rs1()).wrapping_add(instr.imm_s());
+
+    let page = (addr / 4096) as PageNum;
+    let offset = (addr & (4096 as Addr - 1)) as u16;
+    let value = core.reg_read(instr.rs2()) as Byte;
+
+    match core.mem.write_byte(page, offset, value) {
+        Ok(_) => {
+            core.advance_pc();
+            InstructionResult::Normal
+        }
+        Err(_) => InstructionResult::Exception(()),
+    }
+}
+
+pub fn lb(core: &mut Core, instr: Instruction) -> InstructionResult {
+    let addr = core.reg_read(instr.rs1()).wrapping_add(instr.imm_i());
+
+    let page = (addr / 4096) as PageNum;
+    let offset = (addr & (4096 as Addr - 1)) as u16;
+
+    match core.mem.read_byte(page, offset) {
+        Ok(x) => {
+            let x = x as i8 as i64 as DWord;
+            core.reg_write(instr.rd(), x);
+            core.advance_pc();
+            InstructionResult::Normal
+        }
+        Err(_) => InstructionResult::Exception(()),
+    }
+}
+
+pub fn lbu(core: &mut Core, instr: Instruction) -> InstructionResult {
+    let addr = core.reg_read(instr.rs1()).wrapping_add(instr.imm_i());
+
+    let page = (addr / 4096) as PageNum;
+    let offset = (addr & (4096 as Addr - 1)) as u16;
+
+    match core.mem.read_byte(page, offset) {
+        Ok(x) => {
+            let x = x as DWord;
+            core.reg_write(instr.rd(), x);
+            core.advance_pc();
+            InstructionResult::Normal
+        }
+        Err(_) => InstructionResult::Exception(()),
+    }
+}