From bb2b6ba7fd72bbebc3a4490d090f080e7b8628cc Mon Sep 17 00:00:00 2001 From: Kartik Agaram Date: Sat, 4 Aug 2018 17:00:27 -0700 Subject: 4478 --- html/subx/ex4.subx.html | 100 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 100 insertions(+) create mode 100644 html/subx/ex4.subx.html (limited to 'html/subx/ex4.subx.html') diff --git a/html/subx/ex4.subx.html b/html/subx/ex4.subx.html new file mode 100644 index 00000000..609fca41 --- /dev/null +++ b/html/subx/ex4.subx.html @@ -0,0 +1,100 @@ + + + + +Mu - subx/ex4.subx + + + + + + + + + + +
+ 1 ## read a character from stdin, save it to a global, write it to stdout
+ 2 #
+ 3 # To run:
+ 4 #   $ subx translate ex4.subx ex4
+ 5 #   $ subx run ex4
+ 6 
+ 7 == 0x08048074  # code segment, after leaving room for ELF header and segment headers
+ 8 # instruction                     effective address                                                   operand     displacement    immediate
+ 9 # op          subop               mod             rm32          base        index         scale       r32
+10 # 1-3 bytes   3 bits              2 bits          3 bits        3 bits      3 bits        2 bits      2 bits      0/1/2/4 bytes   0/1/2/4 bytes
+11 
+12   ## read(stdin, x, 1)
+13   # fd = 0 (stdin)
+14   bb/copy                                                                                                                         0/imm32           # copy 0 to EBX
+15   # initialize x (location to write result to)
+16   b9/copy                                                                                                                         0x080490a7/imm32  # copy to ECX
+17   # size = 1 character
+18   ba/copy                                                                                                                         1/imm32           # copy 1 to EDX
+19   # read(fd, x, size)
+20   b8/copy                                                                                                                         3/imm32           # copy 3 to EAX
+21   cd/syscall                                                                                                                      0x80/imm8         # int 80h
+22 
+23   ## write(stdout, x, 1)
+24   # fd = 1 (stdout)
+25   bb/copy                                                                                                                         1/imm32           # copy 1 to EBX
+26   # initialize x (location to read from)
+27   b9/copy                                                                                                                         0x080490a7/imm32  # copy to ECX
+28   # size = 1 character
+29   ba/copy                                                                                                                         1/imm32           # copy 1 to EDX
+30   # write(fd, x, size)
+31   b8/copy                                                                                                                         4/imm32           # copy 4 to EAX
+32   cd/syscall                                                                                                                      0x80/imm8         # int 80h
+33 
+34   ## exit(EBX)
+35   b8/copy                                                                                                                         1/imm32           # copy 1 to EAX
+36   cd/syscall                                                                                                                      0x80/imm8         # int 80h
+37 
+38 == 0x080490a7
+39 00 00 00 00  # space for read() to write to
+40 
+41 # vim:ft=subx:nowrap
+
+ + + -- cgit 1.4.1-2-gfad0