// Copyright 2009, 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package runtime
#include "runtime.h"
#include "arch.h"
#include "malloc.h"
#include "go-string.h"
#include "race.h"

#define charntorune(pv, str, len) __go_get_rune(str, len, pv)

const String	runtime_emptystring;

intgo
runtime_findnull(const byte *s)
{
	if(s == nil)
		return 0;
	return __builtin_strlen((const char*) s);
}

static String
gostringsize(intgo l, byte** pmem)
{
	String s;
	byte *mem;

	if(l == 0) {
		*pmem = nil;
		return runtime_emptystring;
	}
	// leave room for NUL for C runtime (e.g., callers of getenv)
	mem = runtime_mallocgc(l+1, FlagNoPointers, 1, 0);
	s.str = mem;
	s.len = l;
	mem[l] = 0;
	*pmem = mem;
	return s;
}

String
runtime_gostring(const byte *str)
{
	intgo l;
	String s;
	byte *mem;

	l = runtime_findnull(str);
	s = gostringsize(l, &mem);
	runtime_memmove(mem, str, l);
	return s;
}

String
runtime_gostringnocopy(const byte *str)
{
	String s;
	
	s.str = str;
	s.len = runtime_findnull(str);
	return s;
}

enum
{
	Runeself	= 0x80,
};

func stringiter(s String, k int) (retk int) {
	int32 l;

	if(k >= s.len) {
		// retk=0 is end of iteration
		retk = 0;
		goto out;
	}

	l = s.str[k];
	if(l < Runeself) {
		retk = k+1;
		goto out;
	}

	// multi-char rune
	retk = k + charntorune(&l, s.str+k, s.len-k);

out:
}

func stringiter2(s String, k int) (retk int, retv int32) {
	if(k >= s.len) {
		// retk=0 is end of iteration
		retk = 0;
		retv = 0;
		goto out;
	}

	retv = s.str[k];
	if(retv < Runeself) {
		retk = k+1;
		goto out;
	}

	// multi-char rune
	retk = k + charntorune(&retv, s.str+k, s.len-k);

out:
}