zx128, microdrive: Microdrive write support

Still somewhat fragile

diff --git a/Kernel/platform-zx128/devmdv.c b/Kernel/platform-zx128/devmdv.c
index e772bbf..17e22cd 100644 (file)
--- a/Kernel/platform-zx128/devmdv.c
+++ b/Kernel/platform-zx128/devmdv.c
@@ -19,6 +19,8 @@ static uint8_t mdv_valid;
 /* Used by the asm helpers */
 uint8_t *mdv_buf;
 uint8_t mdv_hdr_buf[15];
+uint8_t mdv_w_hdr_buf[15+12];
+
 uint8_t mdv_sector;
 uint16_t mdv_len;
 uint8_t mdv_page;
@@ -80,6 +82,11 @@ static int mdv_transfer(uint8_t minor, bool is_read, uint8_t rawflag)
                else
                        err = mdv_bwrite();
                irqrestore(irq);
+               if (err) {
+                       kprintf("mdv%d: %c error %d\n", minor, "wr"[is_read],
+                               err);
+                       goto bad;
+               }
                mdv_buf += 512;
        }
        return 0;

diff --git a/Kernel/platform-zx128/microdrive.s b/Kernel/platform-zx128/microdrive.s
index 5bb5b10..ffd5773 100644 (file)
--- a/Kernel/platform-zx128/microdrive.s
+++ b/Kernel/platform-zx128/microdrive.s
@@ -19,6 +19,10 @@
 ;      there is an "erase" command. When running as a pseudo-floppy we
 ;      don't have that. Instead we keep a blockmap table in physical 1 and
 ;      128.
+;
+;
+;      FIXME: currently if we find the block but get a bad csum we can
+;      loop effectively forever.
 ;
                .module microdrive
 
@@ -31,6 +35,7 @@
                .globl _mdv_sector
                .globl _mdv_buf
                .globl _mdv_hdr_buf
+               .globl _mdv_w_hdr_buf
                .globl _mdv_len
                .globl _mdv_page
                .globl _mdv_csum
@@ -42,6 +47,7 @@
 
 SECTORID       .equ    0x01
 CSUM           .equ    0x0E
+MAP_PREAMBLE   .equ    0x0C
 
 nap_1ms:       push de
                ld de, #87
@@ -57,18 +63,28 @@ napl:               dec de
 ;      Must preserve E
 ;
 mdv_csum_hdr:
+               ld hl, #_mdv_hdr_buf    ; header buffer
+mdv_csum_hdr_2:
+               ld bc, #0x0E01          ; 14 bytes
+               call mdv_csum_data
+               cp (hl)
+               ret
+mdv_csum_w_hdr:
+               ld hl, #_mdv_w_hdr_buf + MAP_PREAMBLE
+               jr mdv_csum_hdr_2
+
+mdv_csum_data:
                xor a
-               ld b, #14
-               ld hl, #_mdv_hdr_buf
-csum_hdr:                              ; check the header is valid
+csum_data2:
                add (hl)
                adc #1
                inc hl
-               jr z, csum_h0
+               jr z, csum_d2
                dec a
-csum_h0:
-               djnz csum_hdr
-               cp (hl)
+csum_d2:
+               djnz csum_data2
+               dec c
+               jr nz, csum_data2
                ret
 
 ;
@@ -237,26 +253,14 @@ mdv_get_blk:      ld hl, #0x0F02          ; 15 + 2 loops (data) + csum in e
                ; Sum the header block
                call mdv_csum_hdr
                jr nz, failblk
-
-
                ld hl, (_mdv_buf)       ; now the data
                ld bc, #2               ; 2 x 256 byte runs
-               xor a
-csum_data2:
-               add (hl)
-               adc #1
-               inc hl
-               jr z, csum_d2
-               dec a
-csum_d2:
-               djnz csum_data2
-               dec c
-               jr nz, csum_data2
-               cp e                            ; expected csum
-               ret z                           ; good block
+               call mdv_csum_data      ; checksum data into a
+               cp e                    ; expected csum
+               ret z                   ; good block
                ld a, #2
                out (0xfe), a
-                       ; try again
+               ; try again
 failblk:
                ret
 
@@ -269,7 +273,7 @@ mdv_put_blk:        ld a, #0xE6
                call nap                        ; May need to be a shade
                                                ; longer. Compare timings
                                                ; with Sinclair ROM
-               ld hl, #_mdv_hdr_buf            ; Header to write first
+               ld hl, #_mdv_w_hdr_buf          ; Header to write first
                ld a, (_mdv_csum)
                ld e, a
                ld a, #0x03                     ; Magneta border
@@ -283,7 +287,7 @@ mdv_put_blk:        ld a, #0xE6
                nop
                nop
                ld c, #0xE7                     ; Data port
-               ld b, #0x1E                     ; Header
+               ld b, #0x0F                     ; Header
                otir                            ; Header bytes out
                ld hl, (_mdv_buf)
                otir                            ; First 256 data
@@ -299,11 +303,37 @@ mdv_put_blk:      ld a, #0xE6
                ret
 
 ;
+;      Template for writes
+buftmplt:
+               .db 0, 0, 0, 0
+               .db 0, 0, 0, 0
+               .db 0, 0, 0xff, 0xff            ; preamble
+               .db 0                           ; block not header
+               .db 0                           ; sector
+               .db 0                           ; length low
+               .db 2                           ; length high
+               .ascii "FUZIX     "             ; filler basically
+;
 ;      Write a sector from memory
 ;
-mdv_store:     in a, (0xef)
+mdv_store:     ld hl, (_mdv_buf)
+               ld bc, #2                       ; 512 bytes
+               call mdv_csum_data              ; checksum into A
+               ld (_mdv_csum), a               ; save ready to write
+               ;
+               ; Now fill in the header on the data bloc
+               ;
+               ld hl, #buftmplt
+               ld de, #_mdv_w_hdr_buf
+               ld bc, #14+MAP_PREAMBLE
+               ldir
+               ld a, (_mdv_sector)             ; fill in the sector
+               ld (_mdv_w_hdr_buf + MAP_PREAMBLE + 1), a
+               call mdv_csum_w_hdr             ; checksum
+               ld (hl), a                      ; fill in the checksum
+               in a, (0xef)
                and #1
-               jr nz, mdv_put_wp               ; write protected
+               jr z, mdv_put_wp                ; write protected
                call mdv_find_hdr               ; find the header we want
                call z, mdv_put_blk             ; write the block after it
                ret                             ; done