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0ee9b2e446
So far the INIT segment was run from the later heap+stack. Now the INIT segment is run from the later BSS. The background is that so far the INIT segment was pretty small (from $80 to $180 bytes). But upcoming changes will increase the INIT segment in certain scenarios up to ~ $1000 bytes. So programs with very limited heap+stack might just not been able to move the INIT segment to its run location. But moving the INIT segment to the later BSS allows it to occupy the later BSS+heap+stack. In order to allow that the constructors are _NOT_ allowed anymore to access the BSS. Rather they must use the DATA segment or the new INITBSS segment. The latter isn't cleared at any point so the constructors may use it to expose values to the main program. However they must make sure to always write the values as they are not pre-initialized.
155 lines
3.7 KiB
ArmAsm
155 lines
3.7 KiB
ArmAsm
;
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; 2002-11-16, Ullrich von Bassewitz
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; 2013-12-23, Greg King
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;
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; int read (int fd, void* buf, unsigned count);
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;
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.export _read
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.constructor initstdin
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.import SETLFS, OPEN, CHKIN, BASIN, CLRCH, BSOUT, READST
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.import rwcommon
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.import popax
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.importzp ptr1, ptr2, ptr3, tmp1, tmp2, tmp3
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.include "cbm.inc"
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.include "errno.inc"
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.include "fcntl.inc"
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.include "filedes.inc"
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;--------------------------------------------------------------------------
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; initstdin: Open the stdin file descriptors for the keyboard
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.segment "INIT"
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.proc initstdin
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lda #STDIN_FILENO + LFN_OFFS
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ldx #CBMDEV_KBD
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ldy #$FF
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jsr SETLFS
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jmp OPEN ; Will always succeed
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.endproc
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;--------------------------------------------------------------------------
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; _read
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.code
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.proc _read
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jsr rwcommon ; Pop params, check handle
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bcs invalidfd ; Invalid handle
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; Check if the LFN is valid and the file is open for writing
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adc #LFN_OFFS ; Carry is already clear
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tax
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lda fdtab-LFN_OFFS,x; Get flags for this handle
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tay
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and #LFN_READ ; File open for writing?
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beq invalidfd
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; Check the EOF flag. If it is set, don't read anything
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tya ; Get flags again
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bmi eof
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; Remember the device number.
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ldy unittab-LFN_OFFS,x
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sty unit
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; Valid lfn. Make it the input file
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jsr CHKIN
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bcc @L3 ; Branch if ok
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jmp __mappederrno ; Store into __oserror, map to errno, return -1
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; Read the next byte
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@L0: jsr BASIN
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sta tmp1 ; Save the input byte
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ldx unit
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bne @L0_1 ; Not keyboard/screen-editor
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cmp #$0D ; Is it a Carriage Return?
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bne @L0_1
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jsr BSOUT ; Yes, echo it (because editor didn't)
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@L0_1: jsr READST ; Read the IEEE status
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sta tmp3 ; Save it
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and #%10111111 ; Check anything but the EOI bit
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bne devnotpresent ; Assume device not present
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; Store the byte just read
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ldy #0
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lda tmp1
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sta (ptr2),y
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inc ptr2
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bne @L1
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inc ptr2+1 ; *buf++ = A;
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; Increment the byte count
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@L1: inc ptr3
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bne @L2
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inc ptr3+1
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; Get the status again and check the EOI bit
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@L2: lda tmp3
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and #%01000000 ; Check for EOI
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bne @L4 ; Jump if end of file reached
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; Decrement the count
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@L3: inc ptr1
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bne @L0
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inc ptr1+1
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bne @L0
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beq done ; Branch always
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; Set the EOI flag and bail out
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@L4: ldx tmp2 ; Get the handle
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lda #LFN_EOF
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ora fdtab,x
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sta fdtab,x
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; Read done, close the input channel
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done: jsr CLRCH
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; Clear _oserror and return the number of chars read
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eof: lda #0
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sta __oserror
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lda ptr3
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ldx ptr3+1
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rts
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; Error entry: Device not present
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devnotpresent:
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lda #ENODEV
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jmp __directerrno ; Sets _errno, clears _oserror, returns -1
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; Error entry: The given file descriptor is not valid or not open
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invalidfd:
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lda #EBADF
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jmp __directerrno ; Sets _errno, clears _oserror, returns -1
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.endproc
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;--------------------------------------------------------------------------
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.bss
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unit: .res 1
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