[directfd] Add cache to end of cylinder option

ghaerr · Nov 7, 2024 · b7371cc · b7371cc
1 parent fd32d9f
commit b7371cc
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Showing 2 changed files with 19 additions and 16 deletions.
diff --git a/elks/arch/i86/drivers/block/directfd.c b/elks/arch/i86/drivers/block/directfd.c
@@ -128,11 +128,15 @@
 char USE_IMPLIED_SEEK = 0; /* =1 for QEMU with 360k/AT stretch floppies (not real hw) */
 #define CHECK_DIR_REG       1   /* =1 to read and clear DIR DSKCHG when media changed */
 #define CHECK_DISK_CHANGE   1   /* =1 to inform kernel of media changed */
-#define FULL_TRACK          1   /* =1 to read full tracks when track caching */
+#define CACHE_CYLINDER      0   /* =1 to cache to end of cylinder rather than track */
+#define FULL_TRACK          0   /* =1 to read full tracks when track caching */
 #define TRACK_SPLIT_BLK     1   /* =1 to read extra sector on track split block */
 #define MOTORDELAY          0   /* =1 to emulate motor on delay for floppy on QEMU */
 #define IODELAY             0   /* =1 to emulate delay for floppy on QEMU */
 
+#define CACHE_CYLINDER_MAX  12  /* max sectors to cache when CACHE_CYLINDER */
+#define CACHE_SIZE          (TRACKSEGSZ >> 9)   /* max usable track cache */
+
 /* adjustable timeouts */
 #define TIMEOUT_MOTOR_ON   (HZ/2)      /* 500 ms wait for floppy motor on before I/O */
 #define TIMEOUT_MOTOR_OFF  (3 * HZ)    /* 3 secs wait for floppy motor off after I/O */
@@ -181,12 +185,6 @@ static unsigned char running;   /* keep track of motors already running */
  */
 #define MIN_ERRORS      0
 
-/*
- * Maximum number of sectors in a track buffer. Track buffering is disabled
- * if tracks are bigger.
- */
-#define MAX_BUFFER_SECTORS 18
-
 #define LINADDR(seg, offs) ((unsigned long)((((unsigned long)(seg)) << 4) + (unsigned)(offs)))
 
 /*
@@ -663,7 +661,7 @@ static void rw_interrupt(void)
     char *cache_offset;
 
     nr = result();
-    /* NOTE: If use_cache is active and sector count is uneven, ST0 will
+    /* NOTE: If cache is active and sector count is uneven, ST0 will
      * always show HD1 as selected at this point. */
     DEBUG("rwI%x|%x|%x-", ST0,ST1,ST2);
 
@@ -732,7 +730,7 @@ static void rw_interrupt(void)
     if (use_cache) {
         cache_drive = current_drive;    /* cache now valid */
         start = (unsigned int)req->rq_sector;
-        cache_start = (FULL_TRACK? start - sector: start);
+        cache_start = ((FULL_TRACK && floppy->sect < CACHE_SIZE)? start - sector: start);
         cache_numsectors = numsectors;
         cache_offset = (char *)(((start - cache_start) << 9) + CACHE_OFF);
         DEBUG("rd %04x:%04x->%08lx:%04x;", CACHE_SEG, cache_offset,
@@ -1204,19 +1202,24 @@ static void DFPROC redo_fd_request(void)
     startsector = sector;
     numsectors = req->rq_nr_sectors;
 #ifdef CONFIG_TRACK_CACHE
-    use_cache = (command == FD_READ) && (req->rq_errors < 4) &&
-        (floppy->sect <= MAX_BUFFER_SECTORS);
+    use_cache = (command == FD_READ) && (req->rq_errors < 4);
     if (use_cache) {
-        if (FULL_TRACK)
+        if (FULL_TRACK && floppy->sect < CACHE_SIZE)
             startsector = 0;
-#if TRACK_SPLIT_BLK
+#if CACHE_CYLINDER
+        numsectors = (floppy->sect << 1) - (sector + head*floppy->sect);
+        if (numsectors > CACHE_CYLINDER_MAX)
+            numsectors = CACHE_CYLINDER_MAX;
+#elif TRACK_SPLIT_BLK
         /* If the floppy sector count is odd, we cache one more sector
          * when head=0 to get an even number of sectors (full blocks).
          */
         numsectors = floppy->sect + (floppy->sect & 1 && !head) - startsector;
 #else
         numsectors = floppy->sect - startsector;
 #endif
+        if (numsectors > CACHE_SIZE)
+            numsectors = CACHE_SIZE;
     }
 #endif
 

diff --git a/elks/include/linuxmt/config.h b/elks/include/linuxmt/config.h
@@ -123,12 +123,12 @@
 
 #if defined(CONFIG_BLK_DEV_BFD) || defined(CONFIG_BLK_DEV_BHD) || defined(CONFIG_BLK_FD)
 #ifdef CONFIG_TRACK_CACHE           /* floppy track buffer in low mem */
-#   define TRACKSEGSZ      0x2400   /* SECTOR_SIZE * 18 (9216) */
+#   define TRACKSEGSZ   0x2400      /* SECTOR_SIZE * 18 (9216) */
 #else
 #  ifdef CONFIG_BLK_FD
-#  define TRACKSEGSZ      0x0400    /* DF driver requires DMASEG internal to TRACKSEG */
+#  define TRACKSEGSZ    0x0400      /* DF driver requires DMASEG internal to TRACKSEG */
 #  else
-#  define TRACKSEGSZ      0         /* no TRACKSEG buffer */
+#  define TRACKSEGSZ    0           /* no TRACKSEG buffer */
 #  endif
 #endif
 #define TRACKSEG        (DMASEG+(DMASEGSZ>>4))