mu/examples/ex4.subx

# 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
4808 - clean up comments in all subx files 2018-12-01 00:45:15 +00:00			`# Read a character from stdin, save it to a global, write it to stdout.`
4392 2018-07-24 18:53:45 +00:00			`#`
4639 2018-10-01 19:28:30 +00:00			`# To run (from the subx directory):`
4893 2018-12-30 08:36:07 +00:00			`# $ ./subx translate examples/ex4.subx -o examples/ex4`
			`# $ ./subx run examples/ex4`
4326 - new example: read() from stdin Currently only runs in emulated mode. Likely a paging issue, writing data to code page. I'm not checking the return value. 2018-07-08 06:38:59 +00:00
switch to new syntax for segment headers in C++ 2019-05-18 07:00:18 +00:00			`== data 0x0a000000`

			`# the global variable we save to`
			`X:`
			`0/imm32 # space for read() to write to`

			`== code 0x09000000`
4780 2018-11-26 08:26:20 +00:00
5410 - 4 examples passing Clean up other examples as well to satisfy the requirements in commit 5404. 2019-07-17 07:47:11 +00:00			`Entry:`
4757 Let's start highlighting all global variables in Red. Assembly programming has a tendency to over-use them. They're a necessary evil, but we should minimize the number of functions that access them. 2018-11-21 03:37:00 +00:00			`# syscall(read, stdin, X, 1)`
4808 - clean up comments in all subx files 2018-12-01 00:45:15 +00:00			`# . fd = 0 (stdin)`
4669 2018-10-06 04:50:20 +00:00			`bb/copy-to-EBX 0/imm32`
4808 - clean up comments in all subx files 2018-12-01 00:45:15 +00:00			`# . data = X (location to write result to)`
4757 Let's start highlighting all global variables in Red. Assembly programming has a tendency to over-use them. They're a necessary evil, but we should minimize the number of functions that access them. 2018-11-21 03:37:00 +00:00			`b9/copy-to-ECX X/imm32`
4808 - clean up comments in all subx files 2018-12-01 00:45:15 +00:00			`# . size = 1 character`
4669 2018-10-06 04:50:20 +00:00			`ba/copy-to-EDX 1/imm32`
4808 - clean up comments in all subx files 2018-12-01 00:45:15 +00:00			`# . syscall`
4669 2018-10-06 04:50:20 +00:00			`b8/copy-to-EAX 3/imm32/read`
			`cd/syscall 0x80/imm8`
4356 - subx: first program with a data segment We read() a character from stdin and write() it out to stdout, saving it to a global variable in between. ELF binaries are inefficient; you can ask for a low alignment, but the kernel may not be able to handle it. If you set up a high alignment then you end up wasting an increasing amount of space in each segment because of the constraint that the offset bear some relationship with the loaded address. 2018-07-16 18:03:08 +00:00
4757 Let's start highlighting all global variables in Red. Assembly programming has a tendency to over-use them. They're a necessary evil, but we should minimize the number of functions that access them. 2018-11-21 03:37:00 +00:00			`# syscall(write, stdout, X, 1)`
4808 - clean up comments in all subx files 2018-12-01 00:45:15 +00:00			`# . fd = 1 (stdout)`
4669 2018-10-06 04:50:20 +00:00			`bb/copy-to-EBX 1/imm32`
4808 - clean up comments in all subx files 2018-12-01 00:45:15 +00:00			`# . initialize X (location to read from)`
4757 Let's start highlighting all global variables in Red. Assembly programming has a tendency to over-use them. They're a necessary evil, but we should minimize the number of functions that access them. 2018-11-21 03:37:00 +00:00			`b9/copy-to-ECX X/imm32`
4808 - clean up comments in all subx files 2018-12-01 00:45:15 +00:00			`# . size = 1 character`
4669 2018-10-06 04:50:20 +00:00			`ba/copy-to-EDX 1/imm32`
4808 - clean up comments in all subx files 2018-12-01 00:45:15 +00:00			`# . syscall`
4669 2018-10-06 04:50:20 +00:00			`b8/copy-to-EAX 4/imm32/write`
			`cd/syscall 0x80/imm8`
4326 - new example: read() from stdin Currently only runs in emulated mode. Likely a paging issue, writing data to code page. I'm not checking the return value. 2018-07-08 06:38:59 +00:00
4698 2018-10-14 19:53:50 +00:00			`# syscall(exit, EBX)`
4669 2018-10-06 04:50:20 +00:00			`b8/copy-to-EAX 1/imm32/exit`
			`cd/syscall 0x80/imm8`
4326 - new example: read() from stdin Currently only runs in emulated mode. Likely a paging issue, writing data to code page. I'm not checking the return value. 2018-07-08 06:38:59 +00:00
4802 Some automated commenting cleanup. Still needs more careful manual scanning. sed -i 's/^# 1-3/# . 1-3/' .subx /.subx sed -i 's/^# op/# . op/' .subx /.subx sed -i 's/# vim/# . . vim/' .subx /.subx sed -i 's/^ # push args/ # . . push args/' .subx /.subx sed -i 's/^ # discard args/ # . . discard args/' .subx /.subx sed -i 's/^ # call/ # . . call/' .subx /.subx sed -i 's/^ # prolog/ # . prolog/' .subx /.subx sed -i 's/^ # epilog/ # . epilog/' .subx /.subx sed -i 's/^ # save registers/ # . save registers/' .subx /.subx sed -i 's/^ # restore registers/ # . restore registers/' .subx /.subx sed -i 's/ operand / register /' .subx /*.subx 2018-11-30 19:10:44 +00:00			`# . . vim:nowrap:textwidth=0`