| 0,0 → 1,112 |
|---|
| fat32_parse_dir: |
| ; in: eax=directory cluster |
| ; out: eax=entry cluster |
| mov bx, 900h |
| mov di, bx |
| push eax |
| call read_cluster |
| mov cx, word [cluster_size] |
| shr cx, 5 ; div 20h |
| .scan_cluster: |
| pop eax |
| cmp byte [di], 0 |
| jz file_not_found |
| mov si, [esp+2] |
| push eax |
| call fat_compare_name |
| jz .file_found |
| and di, not 1Fh |
| add di, 20h |
| loop .scan_cluster |
| pop eax |
| call next_cluster |
| jnc file_not_found |
| jc fat32_parse_dir |
| .file_found: |
| pop eax |
| mov si, [esp+2] |
| mov [cur_obj], si |
| and di, not 1Fh |
| mov si, directory_string |
| mov ax, [di+14h] |
| shl eax, 10h |
| mov ax, [di+1Ah] |
| test eax, eax |
| mov si, nodata_string |
| jz find_error_si |
| ret 2 |
| |
| fat_compare_name: |
| push cx |
| mov cx, 9 |
| .scan: |
| lodsb |
| cmp al, '.' |
| jz .ext |
| cmp al, 0 |
| jz .nameend |
| cmp al, 'a' |
| jb .notletter |
| cmp al, 'z' |
| ja .notletter |
| or byte [di], 20h |
| .notletter: |
| scasb |
| loopz .scan |
| .notfound: |
| inc cx ; to clear ZF flag |
| pop cx |
| ret |
| .ext: |
| mov al, ' ' |
| dec cx |
| repz scasb |
| jnz .notfound |
| test di, 1 |
| jnz .notfound |
| mov cx, 4 |
| jmp .scan |
| .nameend: |
| mov al, ' ' |
| dec cx |
| repz scasb |
| jnz .notfound |
| test di, 1 |
| jnz .file_found |
| mov cx, 3 |
| repz scasb |
| jnz .notfound |
| .file_found: |
| xor cx, cx ; to set ZF flag |
| pop cx |
| ret |
| |
| read_cluster: |
| ; in: eax=cluster,bx->buffer |
| and eax, 0FFFFFFFh |
| movzx ecx, byte [50Dh] ; sects_per_clust |
| mul ecx |
| add eax, [data_start] |
| ; call read |
| ; ret |
| jmp relative_read |
| next_cluster: |
| mov bx, 700h |
| ; sector is 200h bytes long, one entry in FAT occupies 4 bytes => 80h entries in sector |
| push eax |
| shr eax, 7 ; div 80h |
| cmp eax, [fat_cur_sector] |
| jz @f |
| mov [fat_cur_sector], eax |
| add eax, [fat_start] |
| mov cx, 1 |
| call relative_read |
| @@: |
| pop eax |
| and eax, 7Fh |
| mov eax, [700h+eax*4] |
| and eax, 0FFFFFFFh |
| cmp eax, 0FFFFFF7h |
| mov si, bad_cluster_string |
| jz find_error_si |
| ret |