that's a *loop* lol

src/ext/i/mod.rs

@@ -89,13 +89,19 @@ impl Instruction for JALR {
     }
 
     fn match_inst(&self, inst: rv32::Word) -> bool {
-        match_mask!(inst, "xxxxxxxxxxxxxxxxxxxxxxxxx1101111")
+        // testing against print 
+        println!("JALR: {:032b}", inst);
+        println!("JALR: xxxxxxxxxxxxxxxxx000xxxxx1100111");
+        match_mask!(inst, "xxxxxxxxxxxxxxxxx000xxxxx1100111")
     }
 
     fn step(&self, inst: GenInstruction, state: &mut cpu::CPUState) {
         println!("VM > Executing JALR");
         let inst = unsafe { inst.I };
-        
+        let offset = sext(inst.full_imm(), 32);
+        let pc = offset.wrapping_add(state.x[inst.rs1() as usize]);
+        state.x[inst.rd() as usize] = state.pc + rv32::WORD as u32;
+        state.pc = pc - 4;
     }
 }
 
@@ -144,6 +150,7 @@ pub enum ExtensionI {
     LUI(LUI),
     AUIPC(AUIPC),
     JAL(JAL),
+    JALR(JALR),
     ADDI(ADDI),
     ADD(ADD),
 }

test/Makefile

@@ -9,7 +9,7 @@ assemble:
 build:
 	$(GCC_PREFIX)-gcc -Wl,-Ttext=0x0 -nostdlib -march=rv64i -mabi=lp64 -o $(TARGET) $(TARGET).S
 	$(GCC_PREFIX)-objdump -t $(TARGET) > $(TARGET).map
-	$(GCC_PREFIX)-objdump -S $(TARGET) > $(TARGET).lst
+	$(GCC_PREFIX)-objdump -d -M no-aliases $(TARGET) > $(TARGET).lst
 	$(GCC_PREFIX)-objcopy -O binary $(TARGET) $(TARGET).bin
 	$(GCC_PREFIX)-objcopy -O ihex $(TARGET) $(TARGET).hex
 

test/test.S

@@ -1,7 +1,8 @@
-j       main
-lui     x2, 0xFFFFF
-addi    t1, x0, 0x123
-auipc   x3, 0x12345
+lui     x1, 0xFFFFF
+addi    x2, x0, 0x123
+addi    x2, x0, 0x123
+lui     t1, 0x80000 # jalr main into x4 then jump to x4
+jalr    t1, 0x4
 
 main:
     addi t0, x0, 100

test/test.hex

@@ -1,3 +1,3 @@
-:100000006F00000137F1FFFF1303301297513412D4
-:040010009302400611
+:10000000B7F0FFFF130130121301301237030080E5
+:08001000E700430093024006E3
 :00000001FF

test/test.lst

@@ -4,11 +4,12 @@ test:     file format elf64-littleriscv
 
 Disassembly of section .text:
 
-0000000000000000 <main-0x10>:
-   0:	0100006f          	j	10 <main>
-   4:	fffff137          	lui	sp,0xfffff
-   8:	12300313          	li	t1,291
-   c:	12345197          	auipc	gp,0x12345
+0000000000000000 <main-0x14>:
+   0:	fffff0b7          	lui	ra,0xfffff
+   4:	12300113          	addi	sp,zero,291
+   8:	12300113          	addi	sp,zero,291
+   c:	80000337          	lui	t1,0x80000
+  10:	004300e7          	jalr	ra,4(t1) # ffffffff80000004 <__global_pointer$+0xffffffff7fffe7ec>
 
-0000000000000010 <main>:
-  10:	06400293          	li	t0,100
+0000000000000014 <main>:
+  14:	06400293          	addi	t0,zero,100

test/test.map

@@ -4,15 +4,15 @@ test:     file format elf64-littleriscv
 SYMBOL TABLE:
 0000000000000000 l    d  .text	0000000000000000 .text
 0000000000000000 l    d  .riscv.attributes	0000000000000000 .riscv.attributes
-0000000000000000 l    df *ABS*	0000000000000000 ccC0QKeL.o
-0000000000000010 l       .text	0000000000000000 main
-0000000000001814 g       *ABS*	0000000000000000 __global_pointer$
-0000000000001014 g       .text	0000000000000000 __SDATA_BEGIN__
+0000000000000000 l    df *ABS*	0000000000000000 ccC2JIEu.o
+0000000000000014 l       .text	0000000000000000 main
+0000000000001818 g       *ABS*	0000000000000000 __global_pointer$
+0000000000001018 g       .text	0000000000000000 __SDATA_BEGIN__
 0000000000000000         *UND*	0000000000000000 _start
 0000000000001018 g       .text	0000000000000000 __BSS_END__
-0000000000001014 g       .text	0000000000000000 __bss_start
-0000000000001014 g       .text	0000000000000000 __DATA_BEGIN__
-0000000000001014 g       .text	0000000000000000 _edata
+0000000000001018 g       .text	0000000000000000 __bss_start
+0000000000001018 g       .text	0000000000000000 __DATA_BEGIN__
+0000000000001018 g       .text	0000000000000000 _edata
 0000000000001018 g       .text	0000000000000000 _end