builtin: add builtin/wasm_bare (#13078)

vlib/builtin/wasm_bare/libc_impl.v

@@ -0,0 +1,173 @@
+module builtin
+
+import dlmalloc
+
+__global global_allocator dlmalloc.Dlmalloc
+
+[unsafe]
+pub fn memcpy(dest &C.void, src &C.void, n usize) &C.void {
+	dest_ := unsafe { &byte(dest) }
+	src_ := unsafe { &byte(src) }
+	unsafe {
+		for i in 0 .. int(n) {
+			dest_[i] = src_[i]
+		}
+	}
+	return unsafe { dest }
+}
+
+[export: 'malloc']
+[unsafe]
+fn __malloc(n usize) &C.void {
+	return unsafe { global_allocator.malloc(n) }
+}
+
+[unsafe]
+fn strlen(_s &C.void) usize {
+	s := unsafe { &byte(_s) }
+	mut i := 0
+	for ; unsafe { s[i] } != 0; i++ {}
+	return usize(i)
+}
+
+[unsafe]
+fn realloc(old_area &C.void, new_size usize) &C.void {
+	if old_area == 0 {
+		return unsafe { malloc(int(new_size)) }
+	}
+	if new_size == usize(0) {
+		unsafe { free(old_area) }
+		return 0
+	}
+	old_size := unsafe { *(&u64(old_area - sizeof(u64))) }
+	if u64(new_size) <= old_size {
+		return unsafe { old_area }
+	} else {
+		new_area := unsafe { malloc(int(new_size)) }
+		unsafe { memmove(new_area, old_area, usize(old_size)) }
+		unsafe { free(old_area) }
+		return new_area
+	}
+}
+
+[unsafe]
+fn memset(s &C.void, c int, n usize) &C.void {
+	mut s_ := unsafe { &char(s) }
+	for i in 0 .. int(n) {
+		unsafe {
+			s_[i] = char(c)
+		}
+	}
+	return unsafe { s }
+}
+
+[unsafe]
+fn memmove(dest &C.void, src &C.void, n usize) &C.void {
+	dest_ := unsafe { &byte(dest) }
+	src_ := unsafe { &byte(src) }
+	mut temp_buf := unsafe { malloc(int(n)) }
+	for i in 0 .. int(n) {
+		unsafe {
+			temp_buf[i] = src_[i]
+		}
+	}
+
+	for i in 0 .. int(n) {
+		unsafe {
+			dest_[i] = temp_buf[i]
+		}
+	}
+	unsafe { free(temp_buf) }
+	return unsafe { dest }
+}
+
+[export: 'calloc']
+[unsafe]
+fn __calloc(nmemb usize, size usize) &C.void {
+	new_area := unsafe { malloc(int(nmemb) * int(size)) }
+	unsafe { memset(new_area, 0, nmemb * size) }
+	return new_area
+}
+
+fn getchar() int {
+	return 0
+}
+
+fn memcmp(a &C.void, b &C.void, n usize) int {
+	a_ := unsafe { &byte(a) }
+	b_ := unsafe { &byte(b) }
+	for i in 0 .. int(n) {
+		if unsafe { a_[i] != b_[i] } {
+			unsafe {
+				return a_[i] - b_[i]
+			}
+		}
+	}
+	return 0
+}
+
+[export: 'free']
+[unsafe]
+fn __free(ptr &C.void) {
+	unsafe {
+		global_allocator.free_(ptr)
+	}
+}
+
+fn vsprintf(str &char, format &char, ap &byte) int {
+	panic('vsprintf(): string interpolation is not supported in `-freestanding`')
+}
+
+fn vsnprintf(str &char, size usize, format &char, ap &byte) int {
+	panic('vsnprintf(): string interpolation is not supported in `-freestanding`')
+}
+
+enum Errno {
+	enoerror
+	eerror
+}
+
+// not really needed
+fn bare_read(buf &byte, count u64) (i64, Errno) {
+	return 0, Errno.eerror
+}
+
+pub fn bare_print(buf &byte, len u64) {
+}
+
+fn bare_eprint(buf &byte, len u64) {
+}
+
+pub fn write(_fd i64, _buf &byte, _count u64) i64 {
+	return -1
+}
+
+[noreturn]
+fn bare_panic(msg string) {
+	println('V panic' + msg)
+	exit(1)
+}
+
+fn bare_backtrace() string {
+	return 'backtraces are not available with `-freestanding`'
+}
+
+[export: 'exit']
+[noreturn]
+fn __exit(code int) {
+	unsafe {
+		// the only way to abort process execution in WASM
+		mut x := &int(voidptr(0))
+		*x = code
+	}
+	for {}
+}
+
+[export: 'qsort']
+fn __qsort(base voidptr, nmemb usize, size usize, sort_cb FnSortCB) {
+	panic('qsort() is not yet implemented in `-freestanding`')
+}
+
+fn init_global_allocator() {
+	global_allocator = dlmalloc.new(get_wasm_allocator())
+}