| Message ID | 1327308641-14736-2-git-send-email-hpoussin@reactos.org |
|---|---|
| State | New |
| Headers | show |
Hervé Poussineau <hpoussin@reactos.org> writes: > Floppies can be simple or double-sided. However, current code > was only taking the common case into account (ie 2 sides). Impact? Are single sided floppies broken before the patch? How?
Markus Armbruster a écrit : > Hervé Poussineau <hpoussin@reactos.org> writes: > >> Floppies can be simple or double-sided. However, current code >> was only taking the common case into account (ie 2 sides). > > Impact? This repairs single-sided floppies > Are single sided floppies broken before the patch? How? Yes. For head > 0, wrong sector number is calculated, so data is read/written at wrong place on underlying block device. Fortunately, mostly nobody is still using single-sided floppies (only some 360 kB floppies are single-sided), so bug has been neglected since a long time. Hervé
Hervé Poussineau <hpoussin@reactos.org> writes: > Markus Armbruster a écrit : >> Hervé Poussineau <hpoussin@reactos.org> writes: >> >>> Floppies can be simple or double-sided. However, current code >>> was only taking the common case into account (ie 2 sides). >> >> Impact? > > This repairs single-sided floppies > >> Are single sided floppies broken before the patch? How? > > Yes. For head > 0, wrong sector number is calculated, so data is > read/written at wrong place on underlying block device. > > Fortunately, mostly nobody is still using single-sided floppies (only > some 360 kB floppies are single-sided), so bug has been neglected > since a long time. Nice info, thanks. Best put it in the commit message.
Hi, Markus Armbruster a écrit : >>> Are single sided floppies broken before the patch? How? >> Yes. For head > 0, wrong sector number is calculated, so data is >> read/written at wrong place on underlying block device. >> >> Fortunately, mostly nobody is still using single-sided floppies (only >> some 360 kB floppies are single-sided), so bug has been neglected >> since a long time. > > Nice info, thanks. Best put it in the commit message. Will do when respinning the serie Hervé
diff --git a/hw/fdc.c b/hw/fdc.c index 70aa5c7..c1898a6 100644 --- a/hw/fdc.c +++ b/hw/fdc.c @@ -95,16 +95,19 @@ static void fd_init(FDrive *drv) drv->max_track = 0; } +#define NUM_SIDES(drv) ((drv)->flags & FDISK_DBL_SIDES ? 2 : 1) + static int fd_sector_calc(uint8_t head, uint8_t track, uint8_t sect, - uint8_t last_sect) + uint8_t last_sect, uint8_t num_sides) { - return (((track * 2) + head) * last_sect) + sect - 1; + return (((track * num_sides) + head) * last_sect) + sect - 1; } /* Returns current position, in sectors, for given drive */ static int fd_sector(FDrive *drv) { - return fd_sector_calc(drv->head, drv->track, drv->sect, drv->last_sect); + return fd_sector_calc(drv->head, drv->track, drv->sect, drv->last_sect, + NUM_SIDES(drv)); } /* Seek to a new position: @@ -135,7 +138,7 @@ static int fd_seek(FDrive *drv, uint8_t head, uint8_t track, uint8_t sect, drv->max_track, drv->last_sect); return 3; } - sector = fd_sector_calc(head, track, sect, drv->last_sect); + sector = fd_sector_calc(head, track, sect, drv->last_sect, NUM_SIDES(drv)); ret = 0; if (sector != fd_sector(drv)) { #if 0 @@ -1019,7 +1022,8 @@ static void fdctrl_start_transfer(FDCtrl *fdctrl, int direction) ks = fdctrl->fifo[4]; FLOPPY_DPRINTF("Start transfer at %d %d %02x %02x (%d)\n", GET_CUR_DRV(fdctrl), kh, kt, ks, - fd_sector_calc(kh, kt, ks, cur_drv->last_sect)); + fd_sector_calc(kh, kt, ks, cur_drv->last_sect, + NUM_SIDES(cur_drv))); switch (fd_seek(cur_drv, kh, kt, ks, fdctrl->config & FD_CONFIG_EIS)) { case 2: /* sect too big */ @@ -1289,7 +1293,8 @@ static void fdctrl_format_sector(FDCtrl *fdctrl) ks = fdctrl->fifo[8]; FLOPPY_DPRINTF("format sector at %d %d %02x %02x (%d)\n", GET_CUR_DRV(fdctrl), kh, kt, ks, - fd_sector_calc(kh, kt, ks, cur_drv->last_sect)); + fd_sector_calc(kh, kt, ks, cur_drv->last_sect, + NUM_SIDES(cur_drv))); switch (fd_seek(cur_drv, kh, kt, ks, fdctrl->config & FD_CONFIG_EIS)) { case 2: /* sect too big */
Floppies can be simple or double-sided. However, current code was only taking the common case into account (ie 2 sides). Signed-off-by: Hervé Poussineau <hpoussin@reactos.org> --- hw/fdc.c | 17 +++++++++++------ 1 files changed, 11 insertions(+), 6 deletions(-)