diff options
Diffstat (limited to 'src/cpu')
| -rw-r--r-- | src/cpu/chip.rs | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/src/cpu/chip.rs b/src/cpu/chip.rs index f1ebeb8..b4ed8bf 100644 --- a/src/cpu/chip.rs +++ b/src/cpu/chip.rs @@ -111,6 +111,17 @@ impl Flags { carry: 0, } } + + fn get_cond(&self, cond: u8) -> u16 { + match cond { + 0 => { (self.n as u16) << 8 | self.zero as u16 } + 1 => { self.zero as u16 } + 2 => { (self.n as u16) << 8 | self.carry as u16 } + 3 => { self.carry as u16 } + _ => { panic!("Invalid Condition for Flags!") } + + } + } } #[derive(Debug)] @@ -409,7 +420,7 @@ impl Chip { (0b01, 0b110, 0b110) => { self.halt() }, //HALT (0b01, dst_r8, src_r8) => { self.ld_r8_r8(src_r8, dst_r8) }, //LD r8, r8 (0b10, op, r8) => { self.alu_a_r8(op, r8); }, //ALU A, r8 - (0b11, 0b000..=0b011, 0b000) => { }, //RET condition + (0b11, 0b000..=0b011, 0b000) => { self.ret_cond(oct2) }, //RET condition (0b11, 0b100, 0b000) => { self.ldh_i16_a() }, //LD (FF00 + u8), A (0b11, 0b101, 0b000) => { self.add_sp_i8() }, //ADD SP, i8 (0b11, 0b110, 0b000) => { self.ldh_a_i16() }, //LD A, (FF00 + u8) @@ -434,6 +445,19 @@ impl Chip { } + // RETURN based on condition + fn ret(&mut self, ret_code: u8) { + // If condition true, RET + if self.flags.get_cond(ret_code) != 0 { + let low = self.read_memory(self.sp); + self.sp += 1; + let high = self.read_memory(self.sp); + self.sp += 1; + let value = (((high as u16) << 8) as u16) | (low as u16); + self.pc = value; + } + } + // Push to stack fn push_r16(&mut self, r16: u8) { let value = self.get_r16stk_register(r16.into()); |