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authorKartik Agaram <vc@akkartik.com>2020-01-01 17:23:29 -0800
committerKartik Agaram <vc@akkartik.com>2020-01-01 17:23:29 -0800
commit113bae7311b63e55e55160970718d19bfeeb56c3 (patch)
treed2468b58470e173329c7ef6e8da496c2f768b037 /apps/ex6.subx
parent1b050736eea04323e09e5e8e7499c33cee1899d0 (diff)
downloadmu-113bae7311b63e55e55160970718d19bfeeb56c3.tar.gz
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+# Print out a (global variable) string to stdout.
+#
+# To run:
+#   $ ./subx translate init.linux examples/ex6.subx -o examples/ex6
+#   $ ./subx run examples/ex6
+#   Hello, world!
+
+== code
+
+# . op          subop               mod             rm32          base        index         scale       r32
+# . 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
+
+Entry:
+    # write(stdout, X, Size)
+    # . fd = 1 (stdout)
+    bb/copy-to-ebx  1/imm32
+    # . initialize X (location to write result to)
+    b9/copy-to-ecx  X/imm32
+    # . initialize Size
+    8b/copy                         0/mod/indirect  5/rm32/.disp32            .             .           2/r32/edx   Size/disp32     .                 # copy *Size to edx
+    # . syscall
+    e8/call  syscall_write/disp32
+
+    # exit(ebx)
+    e8/call  syscall_exit/disp32
+
+== data
+
+Size:  # size of string
+    0x0e/imm32  # 14
+X:  # string to print
+    48 65 6c 6c 6f 2c 20 77 6f 72 6c 64 21 0a       00
+#   H  e  l  l  o  ,  ␣  w  o  r  l  d  !  newline  null
+
+# . . vim:nowrap:textwidth=0