Mercurial > repos > blastem
changeset 2152:c3ee42c89b27
More accurate seek times and basic emulation of extended time between CDD interrupts during coarse seeking
| author | Michael Pavone <pavone@retrodev.com> |
|---|---|
| date | Wed, 06 Apr 2022 21:44:46 -0700 |
| parents | 01ad74197414 |
| children | 8a30e44e8223 237068a25523 |
| files | cdd_mcu.c cdd_mcu.h |
| diffstat | 2 files changed, 48 insertions(+), 10 deletions(-) [+] |
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--- a/cdd_mcu.c Wed Mar 30 23:20:45 2022 -0700 +++ b/cdd_mcu.c Wed Apr 06 21:44:46 2022 -0700 @@ -85,25 +85,27 @@ // circumference ~ 364.42 mm // ~ 21 sectors per physical track at edge // ~8 sectors per physical track at start of lead-in -#define COARSE_SEEK 2200 //made up numbers -#define FINE_SEEK 10 +#define COARSE_SEEK_TRACKS 57 //estimate based on seek test static void handle_seek(cdd_mcu *context) { - //TODO: more realistic seeking behavior + uint32_t old_coarse = context->coarse_seek; if (context->seeking) { if (context->seek_pba == context->head_pba) { context->seeking = 0; + context->coarse_seek = 0; if (context->status == DS_PAUSE) { context->pause_pba = context->head_pba; } } else { //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 sectors_per_track = circumference / SECTOR_LENGTH; - uint32_t max_seek = sectors_per_track * 190; + uint32_t max_seek = sectors_per_track * COARSE_SEEK_TRACKS; uint32_t min_seek = sectors_per_track; - + uint32_t old_pba = context->head_pba; if (context->seek_pba > context->head_pba) { uint32_t seek_amount; for (seek_amount = max_seek; seek_amount >= min_seek; seek_amount >>= 1) @@ -133,8 +135,15 @@ context->head_pba = 0; } } + if (context->head_pba != old_pba + 1) { + context->coarse_seek++; + } else { + context->coarse_seek = 0; + } } } + if (old_coarse && !context->coarse_seek) { + } } static void lba_to_status(cdd_mcu *context, uint32_t lba) @@ -173,8 +182,13 @@ handle_seek(context); if (!context->seeking) { context->head_pba++; - if (context->head_pba > context->pause_pba + FINE_SEEK) { - context->head_pba = context->pause_pba - FINE_SEEK; + //TODO: better estimate of sectors per track at current head location + float circumference = (MAX_CIRCUMFERENCE-MIN_CIRCUMFERENCE) * ((float)context->head_pba) / (74 * 60 * SECTORS_PER_SECOND) + MIN_CIRCUMFERENCE; + float sectors_per_track = circumference / SECTOR_LENGTH; + //TODO: check the exact behavior during pause on hardware + uint32_t diff = sectors_per_track * 0.5f + 0.5f; + if (context->head_pba > context->pause_pba + diff) { + context->head_pba = context->pause_pba - diff; if (context->head_pba < LEADIN_SECTORS) { context->head_pba = LEADIN_SECTORS; } @@ -216,7 +230,8 @@ break; } uint8_t force_not_ready = 0; - if (context->seeking && context->head_pba - prev_pba != 1) { + if (context->coarse_seek && !(context->coarse_seek % 15)) { + //TODO: adjust seeking for focus error when these bad statuses happen //BIOS depends on getting a not ready status during seeking to clear certain state force_not_ready = context->status_buffer.format != SF_NOTREADY; } @@ -586,6 +601,9 @@ next_nibble = context->last_nibble_cycle + NIBBLE_CLOCKS; } else if (!context->current_status_nibble) { next_nibble = context->last_sector_cycle + PROCESSING_DELAY; + if (context->coarse_seek % 3) { + next_nibble += SECTOR_CLOCKS * (3 - (context->coarse_seek % 3)); + } } else { next_nibble = CYCLE_NEVER; } @@ -594,10 +612,14 @@ for (; context->cycle < cd_cycle; context->cycle += CDD_MCU_DIVIDER) { if (context->cycle >= next_subcode) { + uint32_t old_coarse = context->coarse_seek; context->last_sector_cycle = context->cycle; next_subcode = context->cycle + SECTOR_CLOCKS; update_status(context, gate_array); next_nibble = context->cycle + PROCESSING_DELAY; + if (context->coarse_seek % 3) { + next_nibble += SECTOR_CLOCKS * (3 - (context->coarse_seek % 3)); + } context->current_status_nibble = 0; if (context->next_subcode_int_cycle != CYCLE_NEVER) { context->subcode_int_pending = 1; @@ -610,6 +632,12 @@ } else { context->next_subcode_int_cycle = CYCLE_NEVER; } + if (old_coarse != context->coarse_seek) { + context->next_int_cycle = cd_block_to_mclks(context->cycle + PROCESSING_DELAY + 7 * NIBBLE_CLOCKS); + if (context->coarse_seek % 3) { + context->next_int_cycle += cd_block_to_mclks(SECTOR_CLOCKS * (3 - (context->coarse_seek % 3))); + } + } } if (context->cycle >= next_nibble) { if (context->current_status_nibble == sizeof(cdd_status)) { @@ -634,8 +662,14 @@ gate_array[ga_index] = (value << 8) | (gate_array[ga_index] & 0x00FF); } if (context->current_status_nibble == 7) { - context->int_pending = 1; - context->next_int_cycle = cd_block_to_mclks(context->cycle + SECTOR_CLOCKS); + if (!(context->coarse_seek % 3)) { + context->int_pending = 1; + if (context->coarse_seek) { + context->next_int_cycle = cd_block_to_mclks(context->cycle + 3 * SECTOR_CLOCKS); + } else { + context->next_int_cycle = cd_block_to_mclks(context->cycle + SECTOR_CLOCKS); + } + } } context->current_status_nibble++; context->last_nibble_cycle = context->cycle; @@ -726,6 +760,9 @@ { context->last_sector_cycle = context->cycle; context->next_int_cycle = cd_block_to_mclks(context->cycle + SECTOR_CLOCKS + PROCESSING_DELAY + 7 * NIBBLE_CLOCKS); + if (context->coarse_seek % 3) { + context->next_int_cycle += cd_block_to_mclks(SECTOR_CLOCKS * (3 - (context->coarse_seek % 3))); + } } void cdd_hock_disabled(cdd_mcu *context)