When the user of the DebugSession uses this decision, the debugged
program will be continued until it is either stopped by a singal (e.g
as a reuslt of a breakpoint), or enters a syscall.
functrace traces the function calls a program makes.
It's like strace, but for userspace.
It works by using Debugging functionality to insert breakpoints
at call&ret instructions.
This patch replaces the old variable lookup logic with a new one based
on lexical environments.
This brings us closer to the way JavaScript is actually specced, and
also gives us some basic support for closures.
The interpreter's call stack frames now have a pointer to the lexical
environment for that frame. Each lexical environment can have a chain
of parent environments.
Before calling a Function, we first ask it to create_environment().
This gives us a new LexicalEnvironment for that function, which has the
function's lexical parent's environment as its parent. This allows
inner functions to access variables in their outer function:
function foo() { <-- LexicalEnvironment A
var x = 1;
function() { <-- LexicalEnvironment B (parent: A)
console.log(x);
}
}
If we return the result of a function expression from a function, that
new function object will keep a reference to its parent environment,
which is how we get closures. :^)
I'm pretty sure I didn't get everything right here, but it's a pretty
good start. This is quite a bit slower than before, but also correcter!
The IOAPIC manual states that "Interrupt Mask-R/W. When this bit is 1,
the interrupt signal is masked. Edge-sensitive interrupts signaled on
a masked interrupt pin are ignored." - Therefore we have to ensure that
we disable interrupts globally with cli(), but also to ensure that we
invoke enable_irq() before sending the hardware command that generates
an IRQ almost immediately.
Obviously we don't support many of the common terminals as we're missing
X11, Qt, WxWidgets, Cairo etc. - but at least the "dumb" terminal
(ASCII output) and "canvas" terminal (generates JS to plot on a HTML
<canvas>) are confirmed to be working :^)
This is useful if we want to do something after patching but before
running the configure script - e.g. creating the configure script using
another script :^)
First, before this change, specifying 'force_pio' in the kernel
commandline was meaningless because we nevertheless set the DMA flag to
be enabled.
Also, we had a problem in which we used IO::repeated_out16() in PIO
write method. This might work on buggy emulators, but I suspect that on
real hardware this code will fail.
The most difficult problem was to restore the PIO read operation.
Apparently, it seems that we can't use IO::repeated_in16() here because
it will read zeroed data. Currently we rely on a simple loop that
invokes IO::in16() to a buffer. Also, the interrupt handling stage in
the PIO read method is moved to be handled inside the loop of reading
the requested sectors.
We will no longer create bitmap buffers for canvases that exceed a
total area of (16384 * 16384) pixels. This matches what some other
browser do.
Thanks to @itamar8910 for finding this! :^)
If the area or size_in_bytes calculation for a Gfx::Bitmap would
overflow, we now refuse to create such a bitmap and return nullptr.
Thanks to @itamar8910 for finding this! :^)
