| Yi Kong | 39bbd96 | 2022-01-09 19:41:38 +0800 | [diff] [blame] | 1 | /* Copyright 2021 Alain Knaff. |
| 2 | * This file is part of mtools. |
| 3 | * |
| 4 | * Mtools is free software: you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License as published by |
| 6 | * the Free Software Foundation, either version 3 of the License, or |
| 7 | * (at your option) any later version. |
| 8 | * |
| 9 | * Mtools is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | * GNU General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with Mtools. If not, see <http://www.gnu.org/licenses/>. |
| 16 | * |
| 17 | * "LBA Assist" geometry |
| 18 | */ |
| 19 | |
| 20 | #include "sysincludes.h" |
| 21 | #include "mtools.h" |
| 22 | #include "lba.h" |
| 23 | |
| 24 | int compute_lba_geom_from_tot_sectors(struct device *dev) |
| 25 | { |
| 26 | unsigned int sect_per_track; |
| 27 | uint32_t tracks; |
| 28 | |
| 29 | /* If already fully specified, nothing to do */ |
| 30 | if(dev->heads && dev->sectors && dev->tracks) |
| 31 | return 0; |
| 32 | |
| 33 | /* If tot_sectors missing, return. Hopefully size still |
| 34 | * specified somewhere that will be read at a later stage |
| 35 | * (such as mformat command line) */ |
| 36 | if(dev->tot_sectors == 0) { |
| 37 | return 0; |
| 38 | } |
| 39 | |
| 40 | /* Floppy sizes, allowing for non-standard sizes with slightly |
| 41 | more sectors per track than the default */ |
| 42 | if(dev->tot_sectors && |
| 43 | dev->tot_sectors <= 8640 && dev->tot_sectors % 40 == 0) { |
| 44 | if(dev->tot_sectors <= 540) { |
| 45 | /* double density 48tpi single sided */ |
| 46 | dev->tracks = 40; |
| 47 | dev->heads = 1; |
| 48 | } else if(dev->tot_sectors <= 1080) { |
| 49 | /* double density 48tpi double sided or |
| 50 | 96 tpi single sided */ |
| 51 | |
| 52 | if(dev->heads == 1) |
| 53 | dev->tracks = 80; |
| 54 | else { |
| 55 | dev->tracks = 40; |
| 56 | dev->heads = 2; |
| 57 | } |
| 58 | } else { |
| 59 | /* double density 96tpi double sided, |
| 60 | * high density, extra density */ |
| 61 | dev->tracks = 80; |
| 62 | dev->heads = 2; |
| 63 | } |
| 64 | dev->sectors = |
| 65 | (uint16_t)(dev->tot_sectors / dev->heads / dev->tracks); |
| 66 | } |
| 67 | |
| 68 | |
| 69 | /* Heads or sectors not known => fill them in both... */ |
| 70 | if(!dev->sectors || !dev->heads) { |
| 71 | dev->sectors = 63; |
| 72 | |
| 73 | if (dev->tot_sectors < 16u*dev->sectors*1024) |
| 74 | dev->heads = 16; |
| 75 | else if (dev->tot_sectors < 32u*dev->sectors*1024) |
| 76 | dev->heads = 32; |
| 77 | else if (dev->tot_sectors < 64u*dev->sectors*1024) |
| 78 | dev->heads = 64; |
| 79 | else if (dev->tot_sectors < 128u*dev->sectors*1024) |
| 80 | dev->heads = 128; |
| 81 | else |
| 82 | dev->heads = 255; |
| 83 | } |
| 84 | |
| 85 | /* ... and calculate corresponding tracks */ |
| 86 | if(!dev->tracks) { |
| 87 | sect_per_track = dev->heads * dev->sectors; |
| 88 | tracks = (dev->tot_sectors + sect_per_track - 1) / |
| 89 | sect_per_track; |
| 90 | dev->tracks = tracks; |
| 91 | } |
| 92 | |
| 93 | return 0; |
| 94 | } |