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Apple2: Provide a way to get directory file count

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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.
This commit is contained in:
Colin Leroy-Mira
2024-11-10 13:38:35 +01:00
committed by Oliver Schmidt
parent 36132a437b
commit 40d9f3eed5
9 changed files with 64 additions and 14 deletions
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1
libsrc/apple2/dir.h
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@@ -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];

2
libsrc/apple2/dir.inc
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@@ -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

24
libsrc/apple2/dir_file_count.s Normal file
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@@ -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

21
libsrc/apple2/opendir.s
View File

@@ -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