add jsr, rti, rts

1 files changed, 16 insertions, 7 deletions

diff --git a/cpu.c b/cpu.c
index e63760c..87d68c8 100644
--- a/cpu.c
+++ b/cpu.c
@@ -407,15 +407,23 @@ iny(uint8_t arg)
 }
 
 static void
-jmp(uint8_t arg)
+jmp(uint16_t arg)
 {
         regs.pc = arg;
 }
 
 static void
-jsr(uint8_t arg)
+jsr(uint16_t arg)
 {
-/* TODO: complete this */
+        uint16_t tmp = regs.pc + 2;
+
+        /*
+         * first push high-byte of return address then low-byte
+         * https://www.masswerk.at/6502/6502_instruction_set.html
+         */
+        PUSH((tmp & 0xFF00) >> 8);
+        PUSH(tmp & 0xFF);
+        regs.pc = arg;
 }
 
 static void
@@ -547,13 +555,14 @@ ror(uint8_t arg)
 static void
 rti(uint8_t arg)
 {
-/* TODO: complete this */
+        plp();
+        regs.pc = PULL();
 }
 
 static void
-rts(uint8_t arg)
+rts(void)
 {
-/* TODO: complete this */
+        regs.pc = PULL() + 1;
 }
 
 static void
@@ -1186,7 +1195,7 @@ interpret(void)
                         cycles += 6;
                         break;
                 case 0x60:
-                        rts(opcode_arg(AM_ACC));
+                        rts();
                         cycles += 6;
                         break;
                 case 0xe9: