From 447ec62300831b7506932eda1ff36d3116735113 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Szymon=20Karpi=C5=84ski?= <hugo@staszic.waw.pl>
Date: Sat, 18 Apr 2020 23:10:28 +0200
Subject: [PATCH] jmp no call

---
 brainfuck.asm | 33 ++++++++++++++++-----------------
 1 file changed, 16 insertions(+), 17 deletions(-)

diff --git a/brainfuck.asm b/brainfuck.asm
index 46ff96f..2f87894 100644
--- a/brainfuck.asm
+++ b/brainfuck.asm
@@ -43,11 +43,11 @@ bf_instructions:
         xor rdi, rdi
         call exit
         align 8
-    times 8*('+'-1) ret
+    times 8*('+'-1) hlt
     bf_increment: ; '+' ascii 43
         inc byte [rdi]
         inc rsi
-        ret
+        jmp rbx
         align 8
     bf_in_stub: ; ',' ascii 44
         jmp bf_in
@@ -55,29 +55,28 @@ bf_instructions:
     bf_decr: ; '-' ascii 45
         dec byte [rdi]
         inc rsi
-        ret
+        jmp rbx
         align 8
     bf_out_stub: ; '.' ascii 46
         jmp bf_out
-        ret
         align 8
-    times 8*('<'-'.'-1) ret
+    times 8*('<'-'.'-1) hlt
     bf_left: ; '<' ascii 60
         dec rdi
         inc rsi
-        ret
+        jmp rbx
         align 8
-    times 8*('>'-'<'-1) ret
+    times 8*('>'-'<'-1) hlt
     bf_right: ; '>' ascii 62
         inc rdi
         inc rsi
-        ret
+        jmp rbx
         align 8
-    times 8*('['-'>'-1) ret
+    times 8*('['-'>'-1) hlt
     bf_forward_stub: ; '[' ascii 91
         jmp bf_forward
         align 8
-    times 8*(']'-'['-1) ret
+    times 8*(']'-'['-1) hlt
     bf_backward_stub: ; ']' ascii 93
         jmp bf_backward
         align 8
@@ -88,7 +87,7 @@ bf_instructions:
         jmp bf_jump
         bf_forward_end:
         inc rsi
-        ret
+        jmp rbx
     
     bf_backward:
         cmp byte [rdi], 0
@@ -96,13 +95,13 @@ bf_instructions:
         jmp bf_jump
         bf_backward_end:
         inc rsi
-        ret
+        jmp rbx
     
     bf_jump:
         sub rsi, bf_program
         mov rsi, [8*rsi + bf_jumps]
         inc rsi
-        ret
+        jmp rbx
     
     bf_out:
         push rdi
@@ -114,7 +113,7 @@ bf_instructions:
         pop rsi
         pop rdi
         inc rsi
-        ret
+        jmp rbx
     
     bf_in:
         push rdi
@@ -124,7 +123,7 @@ bf_instructions:
         pop rdi
         mov byte [rdi], al
         inc rsi
-        ret
+        jmp rbx
 
     
 main:
@@ -159,11 +158,11 @@ _jump_loop:
 
 lea rsi, [bf_program]
 lea rdi, [bf_tape]
+lea rbx, [_program_loop]
 _program_loop:
     movzx rax, byte [rsi]
     lea rax, [bf_instructions + 8*rax]
-    call rax
-    jmp _program_loop
+    jmp rax
     
 xor rdi, rdi
 call exit