From d6338e42cc0875e54bdce4b86aa30fe636d667ce Mon Sep 17 00:00:00 2001
From: OBattler <oubattler@gmail.com>
Date: Wed, 7 May 2025 23:08:26 +0200
Subject: [PATCH] Significantly speed up floppy turbo mode when the FDC is
 using DMA.

---
 src/floppy/fdc.c        |  9 +++++++++
 src/floppy/fdd_86f.c    | 18 +++++++++++++++---
 src/include/86box/fdc.h |  1 +
 3 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/floppy/fdc.c b/src/floppy/fdc.c
index de8508e69..e779ea2d7 100644
--- a/src/floppy/fdc.c
+++ b/src/floppy/fdc.c
@@ -279,6 +279,15 @@ fdc_is_mfm(fdc_t *fdc)
     return fdc->mfm ? 1 : 0;
 }
 
+int
+fdc_is_dma(fdc_t *fdc)
+{
+    if ((fdc->flags & FDC_FLAG_PCJR) || !fdc->dma)
+        return 0;
+    else
+        return 1;
+}
+
 void
 fdc_request_next_sector_id(fdc_t *fdc)
 {
diff --git a/src/floppy/fdd_86f.c b/src/floppy/fdd_86f.c
index 0a7120b16..24fde57b1 100644
--- a/src/floppy/fdd_86f.c
+++ b/src/floppy/fdd_86f.c
@@ -2414,16 +2414,28 @@ d86f_turbo_poll(int drive, int side)
         case STATE_0C_READ_DATA:
         case STATE_11_SCAN_DATA:
         case STATE_16_VERIFY_DATA:
-            d86f_turbo_read(drive, side);
+            if (fdc_is_dma(d86f_fdc))
+                for (int i = 0; i < (128 << dev->last_sector.id.n); i++)
+                    d86f_turbo_read(drive, side);
+            else
+                d86f_turbo_read(drive, side);
             break;
 
         case STATE_05_WRITE_DATA:
         case STATE_09_WRITE_DATA:
-            d86f_turbo_write(drive, side);
+            if (fdc_is_dma(d86f_fdc))
+                for (int i = 0; i < (128 << dev->last_sector.id.n); i++)
+                    d86f_turbo_write(drive, side);
+            else
+                d86f_turbo_write(drive, side);
             break;
 
         case STATE_0D_FORMAT_TRACK:
-            d86f_turbo_format(drive, side, (side && (d86f_get_sides(drive) != 2)));
+            if (fdc_is_dma(d86f_fdc))
+                while (dev->state == STATE_0D_FORMAT_TRACK)
+                    d86f_turbo_format(drive, side, (side && (d86f_get_sides(drive) != 2)));
+            else
+                d86f_turbo_format(drive, side, (side && (d86f_get_sides(drive) != 2)));
             return;
 
         case STATE_IDLE:
diff --git a/src/include/86box/fdc.h b/src/include/86box/fdc.h
index 36cfaeb7a..ed62cb45f 100644
--- a/src/include/86box/fdc.h
+++ b/src/include/86box/fdc.h
@@ -206,6 +206,7 @@ extern int         fdc_get_drive(fdc_t *fdc);
 extern int         fdc_get_perp(fdc_t *fdc);
 extern int         fdc_get_format_n(fdc_t *fdc);
 extern int         fdc_is_mfm(fdc_t *fdc);
+extern int         fdc_is_dma(fdc_t *fdc);
 extern double      fdc_get_hut(fdc_t *fdc);
 extern double      fdc_get_hlt(fdc_t *fdc);
 extern void        fdc_request_next_sector_id(fdc_t *fdc);