December 25, 2014, 2:54 pm
JS code can manipuate memory directly using setValue, here’s a quick example of returning by reference. The C code is as follows:
#include <stdio.h>
#include <emscripten.h>
#include <string.h>
int main() {
char buffer[10];
strcpy(buffer,"nothing");
int ret = EM_ASM_INT({
return js_receive($0,$1,$2,$3);
}, 1,buffer,3,4);
printf("returned: %d\n",ret);
printf("buffer : %s\n",buffer);
char call[100];
strcpy(call,"alert('");
strcat(call,buffer);
strcat(call,"')");
emscripten_run_script(call);
}
And can be called using the following JS which modifies the contents of buffer:
<!DOCTYPE html>
<html>
<body>
<script>
function js_receive(a,b,c,d) {
var bstr = Pointer_stringify(b);
document.write(a + " " + bstr + " " + c + " " + d);
setValue(b , 84, 'i8');
setValue(b+1, 87, 'i8');
setValue(b+2, 79, 'i8');
setValue(b+3, 0, 'i8');
return 42;
}
</script>
<script src="calljs.js"></script>
</body>
</html>
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December 24, 2014, 2:03 pm
A very simple for calling JS from C and returning a value. Create the following C program, in the file calljs.c, it makes a single call to js_receive which will be our Javascript function:
#include <stdio.h>
#include <emscripten.h>
int main() {
int ret = EM_ASM_INT({
return js_receive($0,$1,$2,$3);
}, 1,"two",3,4);
printf("returned: %d\n",ret);
}
compile it with: <pre>emcc calljs.c -o calljs.js</pre>
It will then call the JS code which can access the variables and string. Here's an example complete html file:
[sourcecode language="html"]
<!DOCTYPE html>
<html>
<body>
<script>
function js_receive(a,b,c,d) {
var bstr = Pointer_stringify(b);
document.write(a + " " + bstr + " " + c + " " + d);
return 42;
}
</script>
<script src="calljs.js"></script>
</body>
</html>
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December 23, 2014, 12:51 pm
Make sure emscripten is setup and on the path. First, get openssl and libssh2 configured:
export CC=emcc
wget https://www.openssl.org/source/openssl-1.0.1j.tar.gz
tar xvzf openssl-1.0.1j.tar.gz
cd openssl-1.0.1j
./Configure -no-asm -no-apps android
make
git clone git://git.libssh2.org/libssh2.git
cd libssh2
export CFLAGS="-I/home/new/gitcode/jterm/openssl-1.0.1j/include"
./configure --with-libssl-prefix=home/new/gitcode/jterm/openssl-1.0.1j
make
Compile some code!
cd examples
emcc ssh2.c -I../include -I../../openssl-1.0.1j/include -lssh2 -lssl -lcrypto -L../../openssl-1.0.1j -L../src/.libs -static
Which results in a.out.js, but who knows if it does anything useful! I assume not! But it does run:
me@laptop:~/gitcode/jterm/libssh2/example$ nodejs ./a.out.js 127.0.0.1 user password
failed to connect!
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December 22, 2014, 11:00 am
I picked up this spectrum analyzer yesterday. Pictures and manuals below, it has a fault and I may attempt a repair at some point (though it’s on ebay for the moment).
TEK 3066, 3086 Sony Programming
TEK 3066, 3086 User
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