diff options
| -rw-r--r-- | src/lib.rs | 22 | ||||
| -rw-r--r-- | src/memory.rs | 42 |
2 files changed, 58 insertions, 6 deletions
@@ -143,10 +143,22 @@ mod tests { Err(MemoryError::InvalidAddress)); assert_eq!(memory.write_byte(2, 0xF0), Err(MemoryError::InvalidAddress)); + assert_eq!(memory.write_byte(3, 0xF0), + Err(MemoryError::InvalidAddress)); + assert_eq!(memory.write_halfword(0, 0xF0), + Err(MemoryError::InvalidAddress)); + assert_eq!(memory.write_halfword(2, 0xF0), + Err(MemoryError::InvalidAddress)); for address in (4..size).step_by(4) { assert_eq!(memory.write_word(address, 0xF0), Ok(())); assert_eq!(memory.read_word(address), Ok(0xF0)); + assert_eq!(memory.read_halfword(address), Ok(0xF0)); + assert_eq!(memory.read_halfword(address + 2), Ok(0x0)); + assert_eq!(memory.read_byte(address), Ok(0xF0)); + assert_eq!(memory.read_byte(address + 1), Ok(0x0)); + assert_eq!(memory.read_byte(address + 2), Ok(0x0)); + assert_eq!(memory.read_byte(address + 3), Ok(0x0)); } assert_eq!(memory.write_word(0x10, 0x01234567), Ok(())); @@ -155,6 +167,8 @@ mod tests { assert_eq!(memory.read_byte(0x11), Ok(0x45)); assert_eq!(memory.read_byte(0x12), Ok(0x23)); assert_eq!(memory.read_byte(0x13), Ok(0x01)); + assert_eq!(memory.read_halfword(0x10), Ok(0x4567)); + assert_eq!(memory.read_halfword(0x12), Ok(0x0123)); let stall = Err(MemoryError::CacheMiss { stall_cycles: memory.latency(), @@ -183,6 +197,8 @@ mod tests { assert_eq!(dm_cache.read_byte(0x13), Ok(0x01)); assert_eq!(dm_cache.write_word(0x18, 0xBEEFBEEF), Ok(())); assert_eq!(dm_cache.read_word(0x18), Ok(0xBEEFBEEF)); + assert_eq!(dm_cache.read_halfword(0x10), Ok(0x4567)); + assert_eq!(dm_cache.read_halfword(0x12), Ok(0x0123)); assert_eq!(memory_ref.borrow_mut().read_word(0x18), Ok(0xBEEFBEEF)); for _ in 0..100 { @@ -196,5 +212,11 @@ mod tests { assert_eq!(dm_cache.read_word(0x14), Ok(0xDEADBEEF)); assert_eq!(dm_cache.read_word(0x18), Ok(0xBEEFBEEF)); assert_eq!(dm_cache.read_word(0x1C), Ok(0xF0)); + assert_eq!(dm_cache.read_halfword(0x10), Ok(0x4567)); + assert_eq!(dm_cache.read_halfword(0x12), Ok(0x0123)); + + assert_eq!(dm_cache.write_byte(0x10, 0x42), Ok(())); + assert_eq!(dm_cache.write_halfword(0x12, 0x4242), Ok(())); + assert_eq!(memory_ref.borrow_mut().read_word(0x10), Ok(0x42424542)); } } diff --git a/src/memory.rs b/src/memory.rs index a0e1a11..5e630b3 100644 --- a/src/memory.rs +++ b/src/memory.rs @@ -48,8 +48,39 @@ pub trait MemoryInterface { } } - // fn read_halfword(&self, address: isa::Address) -> Result<isa::HalfWord>; - // fn write_halfword(&self, address: isa::Address) -> Result<()>; + // TODO: check address more thoroughly + + fn read_halfword(&mut self, address: isa::Address) -> Result<isa::HalfWord> { + let result = self.read_word(address); + let offset = address & 0b10; + + match result { + Ok(word) => match offset { + 0 => Ok((word & 0xFFFF) as isa::HalfWord), + 2 => Ok(((word & 0xFFFF0000) >> 16) as isa::HalfWord), + _ => panic!("Invalid halfword offset: address {:x}", address), + }, + Err(e) => Err(e), + } + } + + fn write_halfword(&mut self, address: isa::Address, value: isa::HalfWord) -> Result<()> { + let result = self.read_word(address); + let offset = address & 0b10; + let value = value as isa::Word; + + match result { + Ok(word) => { + let value = match offset { + 0 => (word & 0xFFFF0000) | value, + 2 => (word & 0x0000FFFF) | (value << 16), + _ => panic!("Invalid halfword offset: address {:x}", address), + }; + self.write_word(address, value) + }, + Err(e) => Err(e), + } + } fn read_byte(&mut self, address: isa::Address) -> Result<isa::Byte> { let result = self.read_word(address); @@ -61,16 +92,15 @@ pub trait MemoryInterface { 1 => Ok(((word & 0xFF00) >> 8) as isa::Byte), 2 => Ok(((word & 0xFF0000) >> 16) as isa::Byte), 3 => Ok(((word & 0xFF000000) >> 24) as isa::Byte), - _ => panic!(""), + _ => panic!("Invalid byte offset: {:x}", address), }, Err(e) => Err(e), } } fn write_byte(&mut self, address: isa::Address, value: isa::Byte) -> Result<()> { - let offset = address % 4; - let result = self.read_word(address); + let offset = address % 4; let value = value as isa::Word; match result { @@ -80,7 +110,7 @@ pub trait MemoryInterface { 1 => (word & !(0xFF00)) | (value << 8), 2 => (word & !(0xFF0000)) | (value << 16), 3 => (word & !(0xFF000000)) | (value << 24), - _ => panic!(""), + _ => panic!("Invalid byte offset: {:x}", address), }; self.write_word(address, value) }, |