.TH tco_go 3 2025-02-06
.SH NAME
tco_go, tco_args, tco_yield
.SH LIBRARY
Tiny Coroutines
.RI ( libtco ", " \-ltco )
.SH SYNOPSIS
.nf
.B #include <tco.h>
.P
.BI "int tco_go(void (*" f ")(...));"
.B "int tco_args(...);"
.BI "void tco_yield(void);"
.fi
.SH DESCRIPTION
.BR tco_go ()
spawns a coroutine context with its own stack, then saves the current execution
context and switches to the new coroutine.
The coroutine function pointer
.I f
is required to not be inlined
(the
.B coroutine
macro is provided as a convienient way to use the
.BR gcc (1)/ clang (1)
.B noinline
attribute, and to communicate the intented use of a function as a coroutine).
When the scheduler switches back to a context that has called
.BR tco_go (),
it resumes execution from after that call.
.P
.BR tco_args ()
sets the function arguments given to the coroutine spawned by
.BR tco_go ().
.P
.BR tco_yield ()
saves the current execution context and switches to the next scheduled context,
pausing execution of the current coroutine.
Tasks are scheduled in a round-robin fashion.
.P
Functions scheduled as coroutines are automatically deinitialised when they
return.
.SH RETURN VALUE
.BR tco_go ()
returns 0 on success, and a non-zero error code when the coroutine fails to
initialise.
.SH CAVEATS
This library works by preserving the state of the callee-saved registers and
restoring them later when the coroutine is resumed.
This approach may be incompatible with other forms of black magic voodoo, your
mileage may vary.
.P
.BR tco_args ()
currently only supports arguments passed by registers
.RI ( %rdi ", " %rsi ", " %rdx ", " %r10 ", " %r8 ", " %r9 " and " %xmm0-8 ).
Spawning coroutines that take arguments on the stack will result in stack
corruption.
Refer to the System V ABI for more details.
.SH AUTHOR AND LICENSE
Copyright (C) 2025 Aiden Gall
.P
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
.P
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
.P
You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.