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[WebAssembly] wasm.js: implement brk

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This commit is contained in:
Sam Clegg 2018-01-13 08:40:17 -08:00
parent 0c827335e4
commit 3ce20a9f57
1 changed files with 32 additions and 15 deletions
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47
arch/wasm32/wasm.js
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@ -25,6 +25,7 @@ var heap_size_bytes = 16 * 1024 * 1024;
var heap_size_pages = heap_size_bytes / (64 * 1024);
var memory = new WebAssembly.Memory({initial: heap_size_pages, maximum: heap_size_pages})
var heap;
var heap_end;
var heap_uint8;
var heap_uint32;
@ -1333,25 +1334,40 @@ syscall_numbers = (function() {
return mapping;
})();
function syscall_writev(fd, iov, iovcnt) {
// We only know how to write to STDOUT
if (fd != 1)
return -1;
var iov32 = iov / 4;
var rtn = 0;
for (var i = 0; i < iovcnt; i++) {
var ptr = heap_uint32[iov32];
iov32++;
var len = heap_uint32[iov32];
iov32++;
if (len > 0) {
stdio.__write_stdout(stringFromHeap(ptr, len));
rtn += len;
}
}
return rtn;
}
function syscall_brk(value) {
if (value != 0)
heap_end = value;
return heap_end;
}
function syscall_impl(n) {
// Special case for writev(stdout), essentially allowing printf to work
var syscall_args = Array.from(arguments).slice(1);
if (n == syscall_numbers["SYS_writev"]) {
if (arguments[1] == 1) {
var iov = arguments[2] / 4;
var iovcnt = arguments[3];
var rtn = 0;
for (var i = 0; i < iovcnt; i++) {
var ptr = heap_uint32[iov];
iov++;
var len = heap_uint32[iov];
iov++;
if (len > 0) {
stdio.__write_stdout(stringFromHeap(ptr, len));
rtn += len;
}
}
return rtn;
if (syscall_args[0] == 1) {
return syscall_writev(...syscall_args)
}
} else if (n == syscall_numbers["SYS_brk"]) {
return syscall_brk(...syscall_args)
}
// For other syscalls we trace that args and then either return 0 (ignore
@ -1445,6 +1461,7 @@ for (var i = arguments.length - 1; i > 0; --i) {
// Load the main module once the ffi object has been fully populated.
var main_module = arguments[0];
modules[0] = load_wasm(main_module);
heap_end = modules[0].exports.__heap_base
// TODO check that `main` exists in modules[0].exports and error out if not.