1 files changed, 42 insertions, 0 deletions
diff --git a/examples/ex4.subx b/examples/ex4.subx
new file mode 100644
index 00000000..31c1c10c
--- /dev/null
+++ b/examples/ex4.subx
@@ -0,0 +1,42 @@
+# Read a character from stdin, save it to a global, write it to stdout.
+#
+# To run (from the subx directory):
+#   $ ./subx translate examples/ex4.subx -o examples/ex4
+#   $ ./subx run examples/ex4
+
+== data 0x0a000000
+
+# the global variable we save to
+X:
+    0/imm32  # space for read() to write to
+
+== code 0x09000000
+
+Entry:
+# syscall(read, stdin, X, 1)
+# . fd = 0 (stdin)
+bb/copy-to-EBX  0/imm32
+# . data = X (location to write result to)
+b9/copy-to-ECX  X/imm32
+# . size = 1 character
+ba/copy-to-EDX  1/imm32
+# . syscall
+b8/copy-to-EAX  3/imm32/read
+cd/syscall  0x80/imm8
+
+# syscall(write, stdout, X, 1)
+# . fd = 1 (stdout)
+bb/copy-to-EBX  1/imm32
+# . initialize X (location to read from)
+b9/copy-to-ECX  X/imm32
+# . size = 1 character
+ba/copy-to-EDX  1/imm32
+# . syscall
+b8/copy-to-EAX  4/imm32/write
+cd/syscall  0x80/imm8
+
+# syscall(exit, EBX)
+b8/copy-to-EAX  1/imm32/exit
+cd/syscall  0x80/imm8
+
+# . . vim:nowrap:textwidth=0