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blockdev: change GetC API
Instead of waiting, GetC always return immediately, with Z indicating if something was fetched. The "wait" loop is implemented by the called (and in the new `blkGetCW`). This simplifies out-of-bounds verifications for storage blockdevs.
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@ -20,6 +20,7 @@ ret
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#include "tok.asm"
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; TODO: call from core
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unsetZ:
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push bc
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ld b, a
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@ -95,17 +95,18 @@ aciaInt:
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ei
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reti
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; Read a character from the input buffer. If the buffer is empty, loop until
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; there something to fetch. Returns value in A.
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; *** BLOCKDEV ***
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; These function below follow the blockdev API.
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aciaGetC:
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push de
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.loop:
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ld a, (ACIA_BUFWRIDX)
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ld e, a
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ld a, (ACIA_BUFRDIDX)
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cp e
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jr z, .loop ; equal? buffer empty, wait.
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jr z, .nothingToRead ; equal? nothing to read.
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; Alrighty, buffer not empty. let's read.
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ld de, ACIA_BUF
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@ -117,7 +118,12 @@ aciaGetC:
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; And finally, fetch the value.
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ld a, (de)
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cp a ; ensure Z
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jr .end
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.nothingToRead:
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call unsetZ
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.end:
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pop de
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ret
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@ -97,13 +97,21 @@ _blkCall:
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pop ix
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ret
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; Reads one character from selected device and returns its value in A. Always
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; returns a character and waits until read if it has to.
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; Reads one character from selected device and returns its value in A.
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; Sets Z according to whether read was successful: Set if successful, unset
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; if not.
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blkGetC:
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ld iyl, 0
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jr _blkCall
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; Writes character in A in current position in the selected device
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; Repeatedly call blkGetC until the call is a success.
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blkGetCW:
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call blkGetC
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jr nz, blkGetCW
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ret
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; Writes character in A in current position in the selected device. Sets Z
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; according to whether the operation was successful.
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blkPutC:
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ld iyl, 2
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jr _blkCall
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@ -7,7 +7,7 @@
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ASCII_CR .equ 0x0d
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ASCII_LF .equ 0x0a
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; *** CODE ***
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; *** REGISTER FIDDLING ***
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; add the value of A into DE
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addDE:
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@ -59,6 +59,17 @@ callIX:
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jp (ix)
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ret
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; Ensures that Z is unset (more complicated than it sounds...)
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unsetZ:
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push bc
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ld b, a
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inc b
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cp b
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pop bc
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ret
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; *** STRINGS ***
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; Increase HL until the memory address it points to is null for a maximum of
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; 0xff bytes. Returns the new HL value as well as the number of bytes iterated
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; in A.
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@ -32,11 +32,13 @@ _mmapAddr:
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ret
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; if out of bounds, will continually return the last char
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; TODO: add bounds check and return Z accordingly.
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mmapGetC:
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push hl
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call _mmapAddr
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ld a, (hl)
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call _mmapForward
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cp a ; ensure Z
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pop hl
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ret
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@ -77,6 +77,7 @@ shellInit:
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shellLoop:
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; First, let's wait until something is typed.
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SHELL_GETC
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jr nz, shellLoop ; nothing typed? loop
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; got it. Now, is it a CR or LF?
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cp ASCII_CR
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jr z, .do ; char is CR? do!
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