Apple2: Provide a way to get directory file count

The information is available in the directory key block.
Providing it to the user as soon as opendir() is done
can save them costly code.

doc/apple2.sgml

@@ -332,6 +332,7 @@ usage.
 <item>_datetime
 <item>allow_lowercase
 <item>beep
+<item>dir_file_count
 <item>get_ostype
 <item>gmtime_dt
 <item>mktime_dt

doc/apple2enh.sgml

@@ -332,6 +332,7 @@ usage.
 <item>_filetype
 <item>_datetime
 <item>beep
+<item>dir_file_count
 <item>get_ostype
 <item>gmtime_dt
 <item>mktime_dt

doc/funcref.sgml

@@ -97,6 +97,7 @@ function.
 <item>_dos_type
 <item>allow_lowercase
 <item><ref id="beep" name="beep">
+<item><ref id="dir_file_count" name="dir_file_count">
 <item><ref id="get_ostype" name="get_ostype">
 <item><ref id="gmtime_dt" name="gmtime_dt">
 <item><ref id="mktime_dt" name="mktime_dt">
@@ -109,6 +110,7 @@ function.
 <itemize>
 <item>_dos_type
 <item><ref id="beep" name="beep">
+<item><ref id="dir_file_count" name="dir_file_count">
 <item><ref id="get_ostype" name="get_ostype">
 <item><ref id="gmtime_dt" name="gmtime_dt">
 <item><ref id="mktime_dt" name="mktime_dt">
@@ -3524,6 +3526,25 @@ used in presence of a prototype.
 </quote>
 
 
+<sect1>dir_file_count<label id="dir_file_count"><p>
+
+<quote>
+<descrip>
+<tag/Function/Returns the number of files in the directory.
+<tag/Header/<tt/<ref id="apple2.h" name="apple2.h">/
+<tag/Declaration/<tt/unsigned int __fastcall__ dir_file_count(DIR *dir);/
+<tag/Description/<tt/dir_file_count/ is machine dependent and does not exist for
+all supported targets. If it exists, it returns the number of active
+(non-deleted) files in the directory.
+<tag/Notes/<itemize>
+<item>The function does not exist on all platforms.
+</itemize>
+<tag/Availability/cc65 (not all platforms)
+<tag/Example/None.
+</descrip>
+</quote>
+
+
 <sect1>div<label id="div"><p>
 
 <quote>

include/apple2.h

@@ -232,6 +232,11 @@ struct tm* __fastcall__ gmtime_dt (const struct datetime* dt);
 time_t __fastcall__ mktime_dt (const struct datetime* dt);
 /* Converts a ProDOS date/time structure to a time_t UNIX timestamp */
 
+typedef struct DIR DIR;
+
+unsigned int __fastcall__ dir_file_count(DIR *dir);
+/* Returns the number of active files in a ProDOS directory */
+
 #if !defined(__APPLE2ENH__)
 unsigned char __fastcall__ allow_lowercase (unsigned char onoff);
 /* If onoff is 0, lowercase characters printed to the screen via STDIO and

include/dirent.h

@@ -147,7 +147,5 @@ void __fastcall__ seekdir (DIR* dir, long offs);
 
 void __fastcall__ rewinddir (DIR* dir);
 
-
-
 /* End of dirent.h */
 #endif

libsrc/apple2/dir.h

@@ -45,6 +45,7 @@ struct DIR {
     int           fd;
     unsigned char entry_length;
     unsigned char entries_per_block;
+    unsigned int  file_count;
     unsigned char current_entry;
     union {
         unsigned char bytes[512];

libsrc/apple2/dir.inc

@@ -2,8 +2,8 @@
         FD                .word
         ENTRY_LENGTH      .byte
         ENTRIES_PER_BLOCK .byte
+        FILE_COUNT        .word
         CURRENT_ENTRY     .byte
-
         .union
                 BYTES               .byte 512
                 .struct CONTENT

libsrc/apple2/dir_file_count.s

@@ -0,0 +1,24 @@
+;
+; Colin Leroy-Mira <colin@colino.net>, 2024
+;
+; unsigned int __fastcall__ dir_file_count(DIR *dir);
+;
+
+        .export   _dir_file_count
+
+        .importzp ptr1
+
+        .include  "apple2.inc"
+        .include  "dir.inc"
+
+.proc _dir_file_count
+        sta       ptr1
+        stx       ptr1+1
+
+        ldy       #DIR::FILE_COUNT + 1
+        lda       (ptr1),y
+        tax
+        dey
+        lda       (ptr1),y
+        rts
+.endproc

libsrc/apple2/opendir.s

@@ -128,24 +128,23 @@
         ; Read succeeded, populate dir struct
         jsr       popptr1     ; Restore our dir pointer
 
-        ldy       #$24 + DIR::BYTES
-        lda       (ptr1),y    ; ENTRIES_PER_BLOCK
-        pha                   ; Back it up
-
+        ; Get file_count to entry_length from block
+        ldy       #$26 + DIR::BYTES
+:       lda       (ptr1),y
+        pha
         dey
-        lda       (ptr1),y    ; ENTRY_LENGTH
+        cpy       #$23 + DIR::BYTES - 1
+        bne       :-
 
+        ; Set entry_length to file_count in struct
         ldy       #DIR::ENTRY_LENGTH
+:       pla
         sta       (ptr1),y
-
-        pla
-        .assert   DIR::ENTRIES_PER_BLOCK = DIR::ENTRY_LENGTH + 1, error
         iny
-        sta       (ptr1),y
+        cpy       #DIR::CURRENT_ENTRY
+        bne       :-
 
         ; Skip directory header entry
-        .assert   DIR::CURRENT_ENTRY = DIR::ENTRIES_PER_BLOCK + 1, error
-        iny
         lda       #$01
         sta       (ptr1),y