4317 - example program: simple addition

2018-07-06 23:34:10 -07:00 · 2018-07-06 23:34:10 -07:00 · a62f334c60
parent 517a471bc0
commit a62f334c60
2 changed files with 13 additions and 0 deletions
--- a/subx/ex2
+++ b/subx/ex2
--- a/subx/ex2.subx
+++ b/subx/ex2.subx
@ -0,0 +1,13 @@
+## add 1 and 1
+
+# opcode        ModR/M                    SIB                   displacement    immediate
+# instruction   mod, reg, Reg/Mem bits    scale, index, base
+# 1-3 bytes     0/1 byte                  0/1 byte              0/1/2/4 bytes   0/1/2/4 bytes
+  bb                                                                            2a 00 00 00   # copy 0x2a (42) to EBX
+  bb                                                                            42/imm32      # copy 42 to EBX
+  81            c3                                                              1/imm32       # add 1 to EBX
+  # exit
+  05                                                                            01 00 00 00   # copy 1 to EAX
+  cd                                                                            80            # int 80h
+
+# vim:ft=subx