add sectors.go; add fat.datetime

Author: soypat

Diff for: exported.go

@@ -182,14 +182,7 @@ func (finfo *FileInfo) Size() int64 {
 
 // ModTime returns the modification time of the file.
 func (finfo *FileInfo) ModTime() time.Time {
-	// https://www.win.tue.nl/~aeb/linux/fs/fat/fat-1.html
-	hour := int(finfo.ftime >> 11)
-	min := int((finfo.ftime >> 5) & 0x3f)
-	doubleSeconds := int(finfo.ftime & 0x1f)
-	yearSince1980 := int(finfo.fdate >> 9)
-	month := int((finfo.fdate >> 5) & 0xf)
-	day := int(finfo.fdate & 0x1f)
-	return time.Date(yearSince1980+1980, time.Month(month), day, hour, min, 2*doubleSeconds, 0, time.UTC)
+	return finfo.datetime.Time()
 }
 
 // IsDir returns true if the file is a directory.

Diff for: fat.go

@@ -108,12 +108,11 @@ const (
 )
 
 type FileInfo struct {
-	fsize   int64 // File Size.
-	fdate   uint16
-	ftime   uint16
-	fattrib byte
-	altname [sfnBufSize + 1]byte
-	fname   [lfnBufSize + 1]byte
+	fsize    int64 // File Size.
+	datetime datetime
+	fattrib  byte
+	altname  [sfnBufSize + 1]byte
+	fname    [lfnBufSize + 1]byte
 }
 
 type mkfsParam struct {
@@ -1447,7 +1446,7 @@ func (dp *dir) alloc(nent int) (fr fileResult) {
 		}
 		isEx := fsys.fstype == fstypeExFAT
 		dname := dp.dir[dirNameOff]
-		if (isEx && dp.dir[xdirType]&0x80 == 0) || (!isEx && (dname == mskDDEM || dname == 0)) {
+		if (!isEx && (dname == mskDDEM || dname == 0)) || (isEx && dp.dir[xdirType]&0x80 == 0) {
 			// Entry is free.
 			n++
 			if n == nent {
@@ -1975,8 +1974,8 @@ func (dp *dir) get_fileinfo(fno *FileInfo) {
 	}
 	fno.fattrib = dp.dir[dirAttrOff] & amMASK
 	fno.fsize = int64(binary.LittleEndian.Uint32(dp.dir[dirFileSizeOff:]))
-	fno.ftime = binary.LittleEndian.Uint16(dp.dir[dirModTimeOff:])
-	fno.fdate = binary.LittleEndian.Uint16(dp.dir[dirModTimeOff+2:])
+	fno.datetime.time = binary.LittleEndian.Uint16(dp.dir[dirModTimeOff:])
+	fno.datetime.date = binary.LittleEndian.Uint16(dp.dir[dirModTimeOff+2:])
 }
 
 func put_utf8(r rune, buf []byte) int {