From d8bc9c2bdd5fdf9d1d952fe7c2053056f5d00d57 Mon Sep 17 00:00:00 2001 From: Virgil Dupras Date: Thu, 9 May 2019 10:47:57 -0400 Subject: [PATCH] parts/z80/sdc: implement blockdev's GetC --- parts/z80/sdc.asm | 79 +++++++++++++++++++++++++++++++--- recipes/rc2014/sdcard/glue.asm | 10 +++-- 2 files changed, 80 insertions(+), 9 deletions(-) diff --git a/parts/z80/sdc.asm b/parts/z80/sdc.asm index 69f9609..c171b6a 100644 --- a/parts/z80/sdc.asm +++ b/parts/z80/sdc.asm @@ -24,11 +24,12 @@ .equ SDC_BLKSIZE 512 ; *** Variables *** -; Index of the sector currently contained in SDC_BUF -.equ SDC_SECTOR SDC_RAMSTART +; Where the block dev current points to. This is a byte index. Higher 7 bits +; indicate a sector number, lower 9 bits are an offset in the current SDC_BUF. +.equ SDC_PTR SDC_RAMSTART ; Whenever we read a sector, we read a whole block at once and we store it ; in memory. That's where it goes. -.equ SDC_BUF SDC_SECTOR+1 +.equ SDC_BUF SDC_PTR+2 .equ SDC_RAMEND SDC_BUF+SDC_BLKSIZE ; *** Code *** @@ -211,6 +212,9 @@ sdcInitialize: or a ; cp 0 jr nz, .error ; Success! out of idle mode! + ; We initialize out current PTR to 0 + ld hl, 0 + ld (SDC_PTR), hl jr .success .error: @@ -244,9 +248,9 @@ sdcSetBlkSize: ; Read block index specified in A and place the contents in (SDC_BUF). ; Doesn't check CRC. ; Returns 0 in A if success, non-zero if error. -; Returns SDC_BUF in HL sdcReadBlk: push bc + push hl out (SDC_PORT_CSLOW), a ld hl, 0 ; read single block at addr A @@ -292,6 +296,71 @@ sdcReadBlk: inc a ; zero, adjust .end: out (SDC_PORT_CSHIGH), a - ld hl, SDC_BUF + pop hl pop bc ret + +; *** shell cmds *** + +sdcInitializeCmd: + .db "sdci", 0, 0, 0 + call sdcInitialize + call sdcSetBlkSize + ret + +; *** blkdev routines *** + +sdcGetC: + ; SDC_PTR points to the character we're supposed to read right now, but + ; we first have to check whether we need to load a new sector in memory. + ; This is rather easy: if the first 9 bits are zero, then we need to + ; read the sector in the high 7 bits. + push hl + + xor a + ld hl, (SDC_PTR) + cp l ; is L zero? + jr nz, .mem ; non-zero? no need to read a sector + ld a, h + and 0x1 + jr nz, .mem ; if H has first bit set, no need to read a + ; sector + ; Oh, first 9 bits unset. Se need to read a sector + ; H is already in A. We just need a right shift. + rra ; now that's our sector + call sdcReadBlk + jr nz, .error +.mem: + ; Read byte from memory at proper offset + ; Higher 256 bytes or lower ones? + ld a, h + and 0x1 + jr nz, .highbuf + ; We're on the lower part + ld hl, SDC_BUF + jr .read +.highbuf: + ; We're on the higher part + ld hl, SDC_BUF+0x100 +.read: + ; HL is now placed either on the lower or higher half of SDC_BUF and + ; all we need is to increase HL by the number in SDC_PTR's LSB (little + ; endian, remember). + ld a, (SDC_PTR) ; LSB + call addHL + + ; This is it! + ld a, (hl) + + ; before we return A, we need to increase (SDC_PTR) + ld hl, SDC_PTR + inc (hl) + + cp a ; ensure Z + jr .end + +.error: + call unsetZ +.end: + pop hl + ret diff --git a/recipes/rc2014/sdcard/glue.asm b/recipes/rc2014/sdcard/glue.asm index 3bd4f3c..ef3f4c6 100644 --- a/recipes/rc2014/sdcard/glue.asm +++ b/recipes/rc2014/sdcard/glue.asm @@ -35,8 +35,6 @@ init: call blkSel call shellInit - ; TODO - block device creation - ei jp shellLoop @@ -48,16 +46,20 @@ ACIA_RAMSTART .equ RAMSTART STDIO_RAMSTART .equ ACIA_RAMEND #include "stdio.asm" BLOCKDEV_RAMSTART .equ STDIO_RAMEND -BLOCKDEV_COUNT .equ 1 +BLOCKDEV_COUNT .equ 2 #include "blockdev.asm" ; List of devices .dw aciaGetC, aciaPutC, 0, 0 +.dw sdcGetC, 0, 0, 0 + +#include "blockdev_cmds.asm" SHELL_RAMSTART .equ BLOCKDEV_RAMEND .define SHELL_IO_GETC call blkGetCW .define SHELL_IO_PUTC call blkPutC -SHELL_EXTRA_CMD_COUNT .equ 0 +SHELL_EXTRA_CMD_COUNT .equ 3 #include "shell.asm" +.dw sdcInitializeCmd, blkBselCmd, blkSeekCmd .equ SDC_RAMSTART SHELL_RAMEND .equ SDC_PORT_CSHIGH 6