From 80c073a5c4a992598ecaf36c58d2294f6aa766d0 Mon Sep 17 00:00:00 2001 From: David Li Date: Sun, 20 Dec 2015 14:59:22 -0500 Subject: Implement JAL, JALR --- src/isa/mod.rs | 15 ++++++++++++--- src/isa/opcodes.rs | 2 +- src/simulator.rs | 9 ++++++++- 3 files changed, 21 insertions(+), 5 deletions(-) diff --git a/src/isa/mod.rs b/src/isa/mod.rs index 0e3261b..c8aa290 100644 --- a/src/isa/mod.rs +++ b/src/isa/mod.rs @@ -127,9 +127,18 @@ impl Instruction { } pub fn s_imm(&self) -> i32 { - let word = self.word as i32; - let low = (word >> 7) & 0x1F; - let high = (word >> 25) & 0x7F; + let low = (self.word >> 7) & 0x1F; + let high = ((self.word as i32) >> 25) & 0x7F; (high << 7) | low } + + pub fn uj_imm(&self) -> i32 { + // Want zero-extension + let low1 = (self.word >> 21) & 0x3FF; + let low11 = (self.word >> 19) & 0x1; + let low12 = (self.word >> 12) & 0xFF; + // Want sign-extension + let low20 = ((self.word as i32) >> 30) & 0x1; + (low20 << 20) | (low12 << 12) | (low11 << 11) | (low1 << 1) + } } diff --git a/src/isa/opcodes.rs b/src/isa/opcodes.rs index e5763e3..56b9568 100644 --- a/src/isa/opcodes.rs +++ b/src/isa/opcodes.rs @@ -1,6 +1,6 @@ pub const BRANCH: u32 = 0x63; pub const JALR: u32 = 0x67; -pub const JAL: u32 = 0x68; +pub const JAL: u32 = 0x6F; pub const INTEGER_IMMEDIATE: u32 = 0x13; pub const INTEGER_REGISTER: u32 = 0x33; pub const LOAD: u32 = 0x3; diff --git a/src/simulator.rs b/src/simulator.rs index a7140fe..607a3b5 100644 --- a/src/simulator.rs +++ b/src/simulator.rs @@ -105,9 +105,16 @@ impl Simulator { // ret core.running = false; } + else { + let target = ((pc as i32) + inst.i_imm()) as usize; + core.registers.write_word(inst.rd(), pc + 4); + core.pc = target; + } }, isa::opcodes::JAL => { - + let target = ((pc as i32) + inst.uj_imm()) as usize; + core.registers.write_word(inst.rd(), pc + 4); + core.pc = target; } isa::opcodes::BRANCH => { -- cgit v1.2.3