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cc65/libsrc/cbm/filedes.s

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Finally: Commodore file I/O git-svn-id: svn://svn.cc65.org/cc65/trunk@1531 b7a2c559-68d2-44c3-8de9-860c34a00d81
2002-11-16 23:45:15 +00:00
;
; Ullrich von Bassewitz, 16.11.2002
;
; File descriptor management for the POSIX I/O routines
;
Changed run location of INIT segment. 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.
2015-10-14 20:52:09 +00:00
.include "cbm.inc"
Finally: Commodore file I/O git-svn-id: svn://svn.cc65.org/cc65/trunk@1531 b7a2c559-68d2-44c3-8de9-860c34a00d81
2002-11-16 23:45:15 +00:00
.include "filedes.inc"
.code
;--------------------------------------------------------------------------
; freefd: Find a free file handle and return it in X. Return carry clear if we
; found one, return a carry if no free lfns are left.
.proc freefd
ldx #0
clc
loop: lda fdtab,x
beq found
inx
cpx #MAX_FDS
bcc loop
found: rts
.endproc
;--------------------------------------------------------------------------
; Data
Changed run location of INIT segment. 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.
2015-10-14 20:52:09 +00:00
.data
Finally: Commodore file I/O git-svn-id: svn://svn.cc65.org/cc65/trunk@1531 b7a2c559-68d2-44c3-8de9-860c34a00d81
2002-11-16 23:45:15 +00:00
Changed run location of INIT segment. 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.
2015-10-14 20:52:09 +00:00
fdtab: .byte LFN_READ
.byte LFN_WRITE
.byte LFN_WRITE
.res MAX_FDS-3
Finally: Commodore file I/O git-svn-id: svn://svn.cc65.org/cc65/trunk@1531 b7a2c559-68d2-44c3-8de9-860c34a00d81
2002-11-16 23:45:15 +00:00
Changed run location of INIT segment. 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.
2015-10-14 20:52:09 +00:00
unittab:.byte CBMDEV_KBD
.byte CBMDEV_SCREEN
.byte CBMDEV_SCREEN
.res MAX_FDS-3
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