cgen: nofloat for kernel code

vlib/v/gen/c/cgen.v

@@ -619,6 +619,14 @@ fn (mut g Gen) typ(t ast.Type) string {
 }
 
 fn (mut g Gen) base_type(t ast.Type) string {
+	if g.pref.nofloat {
+		// todo compile time if for perf?
+		if t == ast.f32_type {
+			return 'u32'
+		} else if t == ast.f64_type {
+			return 'u64'
+		}
+	}
 	share := t.share()
 	mut styp := if share == .atomic_t { t.atomic_typename() } else { g.cc_type(t, true) }
 	if t.has_flag(.shared_f) {

vlib/v/pref/pref.v

@@ -192,6 +192,7 @@ pub mut:
 	is_cstrict          bool                  // turn on more C warnings; slightly slower
 	assert_failure_mode AssertFailureMode // whether to call abort() or print_backtrace() after an assertion failure
 	message_limit       int = 100 // the maximum amount of warnings/errors/notices that will be accumulated
+	nofloat             bool              // for low level code, like kernels: replaces f32 with u32 and f64 with u64
 	// checker settings:
 	checker_match_exhaustive_cutoff_limit int = 12
 }
@@ -277,6 +278,9 @@ pub fn parse_args(known_external_commands []string, args []string) (&Preferences
 			'-cstrict' {
 				res.is_cstrict = true
 			}
+			'-nofloat' {
+				res.nofloat = true
+			}
 			'-gc' {
 				gc_mode := cmdline.option(current_args, '-gc', '')
 				match gc_mode {