From e0460819000b6f3cb2ceabe18f85738ace2327e4 Mon Sep 17 00:00:00 2001 From: Virgil Dupras Date: Thu, 6 Jun 2019 22:16:28 -0400 Subject: [PATCH] sdc: add second buffer --- kernel/sdc.asm | 100 +++++++++++++++++++++++-------- recipes/rc2014/zasm/cfsin/user.h | 13 ++-- recipes/rc2014/zasm/glue.asm | 5 +- recipes/rc2014/zasm/user.h | 13 ++-- 4 files changed, 89 insertions(+), 42 deletions(-) diff --git a/kernel/sdc.asm b/kernel/sdc.asm index 2d5e81c..f56ec51 100644 --- a/kernel/sdc.asm +++ b/kernel/sdc.asm @@ -46,8 +46,6 @@ ; clean, we use any. This way, as long as writing isn't made to random ; addresses, we ensure that we don't write wastefully because read operations, ; even if random, will always use the one buffer that isn't dirty. -; -; NOTE: the 2-buffers thing is still a work in progress... ; *** Defines *** ; SDC_PORT_CSHIGH: Port number to make CS high @@ -61,13 +59,18 @@ ; This is a pointer to the currently selected buffer. This points to the BUFSEC ; part, that is, two bytes before actual content begins. .equ SDC_BUFPTR SDC_RAMSTART -; Sector number currently in SDC_BUF. -.equ SDC_BUFSEC SDC_BUFPTR+2 +; Sector number currently in SDC_BUF1. +.equ SDC_BUFSEC1 SDC_BUFPTR+2 ; Whether the buffer has been written to. 0 means clean. 1 means dirty. -.equ SDC_BUFDIRTY SDC_BUFSEC+1 +.equ SDC_BUFDIRTY1 SDC_BUFSEC1+1 ; The contents of the buffer. -.equ SDC_BUF SDC_BUFDIRTY+1 -.equ SDC_RAMEND SDC_BUF+SDC_BLKSIZE +.equ SDC_BUF1 SDC_BUFDIRTY1+1 + +; second buffer has the same structure as the first. +.equ SDC_BUFSEC2 SDC_BUF1+SDC_BLKSIZE +.equ SDC_BUFDIRTY2 SDC_BUFSEC2+1 +.equ SDC_BUF2 SDC_BUFDIRTY2+1 +.equ SDC_RAMEND SDC_BUF2+SDC_BLKSIZE ; *** Code *** ; Wake the SD card up. After power up, a SD card has to receive at least 74 @@ -252,12 +255,12 @@ sdcInitialize: jr nz, .error ; Success! out of idle mode! ; initialize variables - ld hl, SDC_BUFSEC + ld hl, SDC_BUFSEC1 ld (SDC_BUFPTR), hl ld a, 0xff - ld (SDC_BUFSEC), a + ld (SDC_BUFSEC1), a xor a - ld (SDC_BUFDIRTY), a + ld (SDC_BUFDIRTY1), a jr .end .error: @@ -411,7 +414,7 @@ sdcWriteBlk: ; good! Now, we need to let the card process this data. It will return ; 0xff when it's not busy any more. call sdcWaitResp - ; Success! Now let's unset the first flag + ; Success! Now let's unset the dirty flag ld hl, (SDC_BUFPTR) inc hl ; dirty flag xor a @@ -430,26 +433,53 @@ sdcWriteBlk: pop hl ret -; Ensures that the sector of the current buffer is in sync with HL, that is, -; that the current buffer in memory corresponds to where HL points to in the SD -; card. If it doesn't, loads the sector specified in the highest 7 bits of HL -; in memory and update the buffer's sector. +; Considering the first 7 bits of HL, select the most appropriate of our two +; buffers and, if necessary, sync that buffer with the SD card. If the selected +; buffer doesn't have the same sector as what HL asks, load that buffer from +; the SD card. ; If the dirty flag is set, we write the content of the in-memory buffer to the ; SD card before we read a new sector. ; Returns Z on success, not-Z on error (with the error code from either ; sdcReadBlk or sdcWriteBlk) sdcSync: - ; HL points to the character we're supposed to read or right now, - ; but we first have to check whether we need to load a new sector in - ; memory. To do this, we compare the high 7 bits of HL with - ; the buffer's sector. If they're different, we need to load a new block. + ; HL points to the character we're supposed to read or right now. Let's + ; extract the wanted sector from this. ld a, h srl a ; A --> the requested sector number - push hl ; <| - ld hl, (SDC_BUFPTR) ; | HL points to sector number - cp (hl) ; | - pop hl ; <| - ret z ; equal? nothing to do + push hl ; Save the requested addr for later + ld l, a + ; Let's first see if our first buffer has our sector + ld a, (SDC_BUFSEC1) + cp l + jr z, .buf1Ok + + ; Ok, let's check for buf2 then + ld a, (SDC_BUFSEC2) + cp l + jr z, .buf2Ok + + ; None of our two buffers have the sector we need, we'll need to load + ; a new one. + + ; We select our buffer depending on which is dirty. If both are on the + ; same status of dirtiness, we pick any (the first in our case). If one + ; of them is dirty, we pick the clean one. + ld hl, SDC_BUFSEC1 + ld a, (SDC_BUFDIRTY1) + or a ; is buf1 dirty? + jr z, .ready ; no? good, that's our buffer + ; yes? then buf2 is our buffer. + ld hl, SDC_BUFSEC2 + +.ready: + ; At this point, HL points to one of our two buffers, the good one. + ; Let's save it to SDC_BUFPTR + ld (SDC_BUFPTR), hl + + ; You remember that HL we saved a long time ago? Now's the time to + ; bring it back. + pop hl + ; We have to read a new sector, but first, let's write the current one ; if needed. call sdcWriteBlk @@ -459,6 +489,17 @@ sdcSync: srl a jp sdcReadBlk ; returns +.buf1Ok: + ld hl, SDC_BUFSEC1 + ld (SDC_BUFPTR), hl + pop hl + ret + +.buf2Ok: + ld hl, SDC_BUFSEC2 + ld (SDC_BUFPTR), hl + pop hl + ret ; *** shell cmds *** @@ -470,6 +511,12 @@ sdcInitializeCmd: ; Flush the current SDC buffer if dirty sdcFlushCmd: .db "sdcf", 0, 0, 0 + ld hl, SDC_BUFSEC1 + ld (SDC_BUFPTR), hl + call sdcWriteBlk + ret nz + ld hl, SDC_BUFSEC2 + ld (SDC_BUFPTR), hl jp sdcWriteBlk ; returns ; *** blkdev routines *** @@ -528,8 +575,11 @@ sdcPutC: pop af ld (hl), a + ; Now, let's set the dirty flag ld a, 1 - ld (SDC_BUFDIRTY), a + ld hl, (SDC_BUFPTR) + inc hl ; point to dirty flag + ld (hl), a ; set dirty flag xor a ; ensure Z jr .end .error: diff --git a/recipes/rc2014/zasm/cfsin/user.h b/recipes/rc2014/zasm/cfsin/user.h index b120a87..539eacb 100644 --- a/recipes/rc2014/zasm/cfsin/user.h +++ b/recipes/rc2014/zasm/cfsin/user.h @@ -1,6 +1,6 @@ .equ USER_CODE 0x8600 .equ USER_RAMSTART USER_CODE+0x1800 -.equ FS_HANDLE_SIZE 8 +.equ FS_HANDLE_SIZE 6 .equ BLOCKDEV_SIZE 8 ; *** JUMP TABLE *** @@ -16,13 +16,12 @@ .equ parseHex 0x1e .equ parseHexPair 0x21 .equ blkSel 0x24 -.equ fsFindFN 0x27 -.equ fsOpen 0x2a -.equ fsGetC 0x2d -.equ fsSeek 0x30 -.equ fsTell 0x33 +.equ blkSet 0x27 +.equ fsFindFN 0x2a +.equ fsOpen 0x2d +.equ fsGetC 0x30 +.equ cpHLDE 0x33 -.equ cpHLDE 0x3b .equ parseArgs 0x3e .equ printstr 0x41 .equ _blkGetC 0x44 diff --git a/recipes/rc2014/zasm/glue.asm b/recipes/rc2014/zasm/glue.asm index 8066541..6dad3c3 100644 --- a/recipes/rc2014/zasm/glue.asm +++ b/recipes/rc2014/zasm/glue.asm @@ -23,18 +23,17 @@ jp parseHex jp parseHexPair jp blkSel + jp blkSet jp fsFindFN jp fsOpen jp fsGetC - jp fsSeek - jp fsTell ; approaching 0x38... + jp cpHLDE ; approaching 0x38... ; interrupt hook .fill 0x38-$ jp aciaInt ; *** Jump Table (cont.) *** - jp cpHLDE jp parseArgs jp printstr jp _blkGetC diff --git a/recipes/rc2014/zasm/user.h b/recipes/rc2014/zasm/user.h index b120a87..539eacb 100644 --- a/recipes/rc2014/zasm/user.h +++ b/recipes/rc2014/zasm/user.h @@ -1,6 +1,6 @@ .equ USER_CODE 0x8600 .equ USER_RAMSTART USER_CODE+0x1800 -.equ FS_HANDLE_SIZE 8 +.equ FS_HANDLE_SIZE 6 .equ BLOCKDEV_SIZE 8 ; *** JUMP TABLE *** @@ -16,13 +16,12 @@ .equ parseHex 0x1e .equ parseHexPair 0x21 .equ blkSel 0x24 -.equ fsFindFN 0x27 -.equ fsOpen 0x2a -.equ fsGetC 0x2d -.equ fsSeek 0x30 -.equ fsTell 0x33 +.equ blkSet 0x27 +.equ fsFindFN 0x2a +.equ fsOpen 0x2d +.equ fsGetC 0x30 +.equ cpHLDE 0x33 -.equ cpHLDE 0x3b .equ parseArgs 0x3e .equ printstr 0x41 .equ _blkGetC 0x44