Mercurial > repos > blastem
changeset 2347:047253715fd8
Minor fix to seek time calculation
| author | Michael Pavone <pavone@retrodev.com> |
|---|---|
| date | Wed, 11 Oct 2023 11:36:18 -0700 |
| parents | 0111c8344477 |
| children | 2025ba21026a |
| files | cdd_mcu.c |
| diffstat | 1 files changed, 11 insertions(+), 9 deletions(-) [+] |
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--- a/cdd_mcu.c Sat Oct 07 18:04:35 2023 -0700 +++ b/cdd_mcu.c Wed Oct 11 11:36:18 2023 -0700 @@ -20,14 +20,14 @@ //track pitch 1.6 um //1250 physical tracks in between //linear speed 1.2 m/s - 1.4 m/s -// 1.3 m = 1300 mm +// 1.2 m = 1200 mm // circumference at 46 mm ~ 144.51 mm // circumference at 50 mm ~ 157.08 mm // avg is 150.795 // 75 sectors per second -// 17.3333 mm "typical" length of a sector -// ~8.7 sectors per track in lead-in area -#define LEADIN_SECTORS 10875 +// 16 mm "typical" length of a sector +// ~9.4 sectors per track in lead-in area +#define LEADIN_SECTORS 11780 static uint32_t cd_block_to_mclks(uint32_t cycles) { @@ -82,12 +82,14 @@ #define MIN_CIRCUMFERENCE 144.51f #define MAX_CIRCUMFERENCE 364.42f -#define SECTOR_LENGTH 17.3333f +#define SECTOR_LENGTH 16.0f // max diameter for program area 116 mm // circumference ~ 364.42 mm -// ~ 21 sectors per physical track at edge -// ~8 sectors per physical track at start of lead-in -#define COARSE_SEEK_TRACKS 57 //estimate based on seek test +// ~ 23 sectors per physical track at edge +// ~9 sectors per physical track at start of lead-in +// seek test suggests average somewhere around 54-60 tracks for a long seek, with a peak around 80 +// Sonic CD title screen seems to need a much higher value to get reasonable sync +#define COARSE_SEEK_TRACKS 60 static void handle_seek(cdd_mcu *context) { uint32_t old_coarse = context->coarse_seek; @@ -102,7 +104,7 @@ //TODO: better estimate of sectors per track at current head location //TODO: drive will periodically lose tracking when seeking which slows //things down from this ideal speed I'm curently estimating - float circumference = (MAX_CIRCUMFERENCE-MIN_CIRCUMFERENCE) * ((float)context->head_pba) / (74 * 60 * SECTORS_PER_SECOND) + MIN_CIRCUMFERENCE; + float circumference = (MAX_CIRCUMFERENCE-MIN_CIRCUMFERENCE) * ((float)context->head_pba) / ((74 * 60 + 41) * SECTORS_PER_SECOND + LEADIN_SECTORS + 22) + MIN_CIRCUMFERENCE; float sectors_per_track = circumference / SECTOR_LENGTH; uint32_t max_seek = sectors_per_track * COARSE_SEEK_TRACKS; uint32_t min_seek = sectors_per_track;