From 413dfa8f25946087778c5e45fcb66edf8f41bc14 Mon Sep 17 00:00:00 2001
From: FeralChild64 <you@example.com>
Date: Mon, 1 Mar 2021 19:45:39 +0100
Subject: [PATCH] some code for floppy sector reading

---
 src/aliases/,aliases_hardware_m65.s           | 21 ++++++++
 src/dos_m65/,aliases_dos.s                    |  6 +--
 .../dev_floppy/dev_fd_util_readsector.s       | 52 +++++++++++++++++++
 3 files changed, 76 insertions(+), 3 deletions(-)
 create mode 100644 src/dos_m65/dev_floppy/dev_fd_util_readsector.s

diff --git a/src/aliases/,aliases_hardware_m65.s b/src/aliases/,aliases_hardware_m65.s
index 4c5126e4..4fde6888 100644
--- a/src/aliases/,aliases_hardware_m65.s
+++ b/src/aliases/,aliases_hardware_m65.s
@@ -29,6 +29,27 @@
 
 	!addr VIC_PALSEL      = $D070 ;          - palette selection register
 
+	; Floppy controller registers
+
+	!addr FDC_CONTROL     = $D080
+	!addr FDC_COMMAND     = $D081
+	!addr FDC_STATUS_A    = $D082
+	!addr FDC_STATUS_B    = $D083
+	!addr FDC_TRACK       = $D084
+	!addr FDC_SECTOR      = $D085
+	!addr FDC_SIDE        = $D086
+	!addr FDC_DATA        = $D087
+	!addr FDC_CLOCK       = $D088
+	!addr FDC_STEP        = $D089
+	!addr FDC_PCODE       = $D08A
+
+	!addr FDC_DBG0        = $D6A0
+	!addr FDC_DBG1        = $D6A1
+	!addr FDC_DATARATE    = $D6A2
+	!addr FDC_LAST_TRACK  = $D6A3
+	!addr FDC_LAST_SECTOR = $D6A4
+	!addr FDC_LAST_SIODE  = $D6A5
+
 	; Palette memory areas
 
 	!addr PALETTE_R       = $D100
diff --git a/src/dos_m65/,aliases_dos.s b/src/dos_m65/,aliases_dos.s
index 8a11c5f6..6416122c 100644
--- a/src/dos_m65/,aliases_dos.s
+++ b/src/dos_m65/,aliases_dos.s
@@ -48,10 +48,10 @@
 	!addr par_LDA_nnnn_Y   = $8015 ; - 2 bytes; address in buffer, ram disk
 	!addr code_RTS_04      = $8017 ; - RTS instruction
 
-	; Parameters for utilities/helkpers
+	; Parameters for utilities/helpers
 
-	!addr PAR_TRACK        = $8018 ; track number for status/error
-	!addr PAR_SECTOR       = $8019 ; sector number for status/error	
+	!addr PAR_TRACK        = $8018 ; track number, also for status/error
+	!addr PAR_SECTOR       = $8019 ; sector number, also for status/error	
 
 	!addr PAR_FSIZE_BYTES  = $801A ; 4 bytes - file size in bytes
 	!addr PAR_FSIZE_BLOCKS = $801E ; 2 bytes - file size in blocks
diff --git a/src/dos_m65/dev_floppy/dev_fd_util_readsector.s b/src/dos_m65/dev_floppy/dev_fd_util_readsector.s
new file mode 100644
index 00000000..6d3747e7
--- /dev/null
+++ b/src/dos_m65/dev_floppy/dev_fd_util_readsector.s
@@ -0,0 +1,52 @@
+
+; Read a single sector from a floppy drive
+
+
+; XXX utilize this
+
+dev_fd_util_readsector:
+
+	; Select FDD sector as buffer
+
+	lda #%10000000                     ; select floppy buffer
+	trb SD_BUFCTL
+
+	lda #%00000100
+	trb FDC_CONTROL                    ; set side 0
+
+	; Select physical track and sector based on logical ones from PAR_TRACK and PAR_SECTOR
+
+	lda PAR_TRACK
+	dec
+	sta FDC_TRACK
+
+	lda FDC_SECTOR
+	cmp #20
+	bcc @side0
+
+@side1:
+	
+	ldx #$01
+	sec
+	sbc #20
+	+skip_2_bytes_trash_nvz
+
+@side0:
+
+	ldx #$00
+	stx FDC_SIDE
+	clc
+	ror
+	sta FDC_SECTOR
+
+	; Ask the controller to read the sector
+
+	lda #$40
+	sta FDC_COMMAND
+@lp:
+	lda FDC_STATUS_B                   ; XXX detect errors here
+	bpl @lp
+
+	; Copy sector to buffer in RAM
+
+	; XXX