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Attempt to optimize hard disk timings by reducing if's.

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This commit is contained in:
OBattler
2022-07-13 03:32:42 +02:00
parent 34006b4cd5
commit f47b20a824
1 changed files with 19 additions and 0 deletions
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19
src/disk/hdd.c
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@@ -165,6 +165,12 @@ hdd_seek_get_time(hard_disk_t *hdd, uint32_t dst_addr, uint8_t operation, uint8_
break;
}
#ifndef OLD_CODE
double continuous_times[2][2] = { { hdd->head_switch_usec, hdd->cyl_switch_usec },
{ zone->sector_time_usec, zone->sector_time_usec } };
double times[2] = { 50.0, hdd->avg_rotation_lat_usec };
#endif
uint32_t new_track = zone->start_track + ((dst_addr - zone->start_sector) / zone->sectors_per_track);
uint32_t new_cylinder = new_track / hdd->phy_heads;
uint32_t cylinder_diff = abs((int)hdd->cur_cylinder - (int)new_cylinder);
@@ -174,6 +180,7 @@ hdd_seek_get_time(hard_disk_t *hdd, uint32_t dst_addr, uint8_t operation, uint8_
double seek_time = 0.0;
if (continuous) {
#ifdef OLD_CODE
if (new_track == hdd->cur_track) {
// Same track
seek_time = zone->sector_time_usec;
@@ -184,19 +191,31 @@ hdd_seek_get_time(hard_disk_t *hdd, uint32_t dst_addr, uint8_t operation, uint8_
// Sequential cylinder
seek_time = hdd->cyl_switch_usec;
}
#else
seek_time = continuous_times[new_track == hdd->cur_track][!!cylinder_diff];
#endif
} else {
if (!cylinder_diff) {
#ifdef OLD_CODE
if (operation != HDD_OP_SEEK) {
seek_time = hdd->avg_rotation_lat_usec;
} else {
//seek_time = hdd->cyl_switch_usec;
seek_time = 50.0;
}
#else
seek_time = times[operation != HDD_OP_SEEK];
#endif
} else {
#ifdef OLD_CODE
seek_time = hdd->cyl_switch_usec + (hdd->full_stroke_usec * (double)cylinder_diff / (double)hdd->phy_cyl);
if (operation != HDD_OP_SEEK) {
seek_time += hdd->avg_rotation_lat_usec;
}
#else
seek_time = hdd->cyl_switch_usec + (hdd->full_stroke_usec * (double)cylinder_diff / (double)hdd->phy_cyl) +
((operation != HDD_OP_SEEK) * hdd->avg_rotation_lat_usec);
#endif
}
}