Expand description
CoreVM’s guest API.
Functions exposed to the guest programs running in an inner VM. ⚠️ CoreVM API is subject to change.
§How to write a program for CoreVM
§Rust
CoreVM programs have single entry-point called main
with index = 0
(the default).
The simplest program looks like the following.
#![no_std]
#![no_main]
#[polkavm_derive::polkavm_export]
extern "C" fn main() -> u64 {
0
}
CoreVM programs produce output into one of the output streams. Currently console and video streams are available. The simplest program that outputs “Hello world” to the console output stream is shown below.
#![no_std]
#![no_main]
use corevm_guest::println;
#[polkavm_derive::polkavm_export]
extern "C" fn main() -> u64 {
println!("Hello world");
0
}
Copying out the data is an atomic operation:
the array passed to e.g. yield_console_data
is either fully copied or not copied at all.
If the array can’t be copied, the program execution is suspended, and
the continuation is possible via creating another work package.
§C
Here is the example program written in C.
#include <stdint.h>
#include "corevm_guest.h"
POLKAVM_EXPORT(uint64_t, ext_main);
uint64_t ext_main() {
corevm_printf("Hello world\n");
return 0;
}
Modules§
- c
- C API.
Macros§
- eprint
- Print a message to the standard error stream.
- eprintln
- Print a message to the standard error stream, with a newline.
- Print a message to the standard output stream.
- println
- Print a message to the standard output stream, with a newline.
Structs§
- Video
Mode - Video monitor output mode.
Enums§
- Console
Stream - Console stream type.
- Video
Frame Format - The format of the frames emitted via
yield_video_frame
.
Functions§
- alloc⚠
- Allocate memory block of the specified size.
- free⚠
- Deallocate the memory block of the specified size starting at
address
. - gas
- Get the current amount of gas.
- stderr
- Get standard error stream.
- stdout
- Get standard output stream.
- video_
mode - Set video monitor output mode to
mode
. - yield_
console_ data - Append
text
to the specified console output stream. - yield_
video_ frame - Append video frame to the video output stream.