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cc65/libsrc/common/moveinit.s

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Adapted, to the c64 target, the INIT-segment overlay scheme from the apple2 targets. When a program starts running, INIT is moved from one place to another place. Then, INIT's code is executed; and, the first place is re-used for variables. After the INIT code has finished, the second place can be re-used by the heap and the C stack. That means that initiation code and data won't waste any RAM space after they stop being needed.
2015-10-05 09:47:43 +00:00
;
Reduced the size of the moveinit subroutine. Made other changes that were recommended by Oliver. * Changed its name from move_init to moveinit. * Used self-modifying code in the subroutine. * The INIT segment doesn't need to be optional (it's used by the start-up file).
2015-10-07 18:56:14 +00:00
; 2015-10-07, Greg King
Adapted, to the c64 target, the INIT-segment overlay scheme from the apple2 targets. When a program starts running, INIT is moved from one place to another place. Then, INIT's code is executed; and, the first place is re-used for variables. After the INIT code has finished, the second place can be re-used by the heap and the C stack. That means that initiation code and data won't waste any RAM space after they stop being needed.
2015-10-05 09:47:43 +00:00
;
Reduced the size of the moveinit subroutine. Made other changes that were recommended by Oliver. * Changed its name from move_init to moveinit. * Used self-modifying code in the subroutine. * The INIT segment doesn't need to be optional (it's used by the start-up file).
2015-10-07 18:56:14 +00:00
.export moveinit
Adapted, to the c64 target, the INIT-segment overlay scheme from the apple2 targets. When a program starts running, INIT is moved from one place to another place. Then, INIT's code is executed; and, the first place is re-used for variables. After the INIT code has finished, the second place can be re-used by the heap and the C stack. That means that initiation code and data won't waste any RAM space after they stop being needed.
2015-10-05 09:47:43 +00:00
.import __INIT_LOAD__, __INIT_RUN__, __INIT_SIZE__ ; Linker-generated
.macpack cpu
.macpack generic
Reduced the size of the moveinit subroutine. Made other changes that were recommended by Oliver. * Changed its name from move_init to moveinit. * Used self-modifying code in the subroutine. * The INIT segment doesn't need to be optional (it's used by the start-up file).
2015-10-07 18:56:14 +00:00
; Put this in the DATA segment because it is self-modifying code.
.data
Adapted, to the c64 target, the INIT-segment overlay scheme from the apple2 targets. When a program starts running, INIT is moved from one place to another place. Then, INIT's code is executed; and, the first place is re-used for variables. After the INIT code has finished, the second place can be re-used by the heap and the C stack. That means that initiation code and data won't waste any RAM space after they stop being needed.
2015-10-05 09:47:43 +00:00
; Move the INIT segment from where it was loaded (over the bss segments)
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
; into where it must be run (over the BSS segment). The two areas might overlap;
; and, the segment is moved upwards. Therefore, this code starts at the highest
Adapted, to the c64 target, the INIT-segment overlay scheme from the apple2 targets. When a program starts running, INIT is moved from one place to another place. Then, INIT's code is executed; and, the first place is re-used for variables. After the INIT code has finished, the second place can be re-used by the heap and the C stack. That means that initiation code and data won't waste any RAM space after they stop being needed.
2015-10-05 09:47:43 +00:00
; address, and decrements to the lowest address. The low bytes of the starting
; pointers are not sums. The high bytes are sums; but, they do not include the
; carry. Both the low-byte sums and the carries will be done when the pointers
; are indexed by the .Y register.
Reduced the size of the moveinit subroutine. Made other changes that were recommended by Oliver. * Changed its name from move_init to moveinit. * Used self-modifying code in the subroutine. * The INIT segment doesn't need to be optional (it's used by the start-up file).
2015-10-07 18:56:14 +00:00
moveinit:
Adapted, to the c64 target, the INIT-segment overlay scheme from the apple2 targets. When a program starts running, INIT is moved from one place to another place. Then, INIT's code is executed; and, the first place is re-used for variables. After the INIT code has finished, the second place can be re-used by the heap and the C stack. That means that initiation code and data won't waste any RAM space after they stop being needed.
2015-10-05 09:47:43 +00:00
; First, move the last, partial page.
; Then, move all of the full pages.
ldy #<__INIT_SIZE__ ; size of partial page
Reduced the size of the moveinit subroutine. Made other changes that were recommended by Oliver. * Changed its name from move_init to moveinit. * Used self-modifying code in the subroutine. * The INIT segment doesn't need to be optional (it's used by the start-up file).
2015-10-07 18:56:14 +00:00
ldx #>__INIT_SIZE__ + (<__INIT_SIZE__ <> 0) ; number of pages, including partial
L1: dey
init_load:
lda __INIT_LOAD__ + (__INIT_SIZE__ & $FF00) - $0100 * (<__INIT_SIZE__ = 0),y
init_run:
sta __INIT_RUN__ + (__INIT_SIZE__ & $FF00) - $0100 * (<__INIT_SIZE__ = 0),y
Adapted, to the c64 target, the INIT-segment overlay scheme from the apple2 targets. When a program starts running, INIT is moved from one place to another place. Then, INIT's code is executed; and, the first place is re-used for variables. After the INIT code has finished, the second place can be re-used by the heap and the C stack. That means that initiation code and data won't waste any RAM space after they stop being needed.
2015-10-05 09:47:43 +00:00
tya
Reduced the size of the moveinit subroutine. Made other changes that were recommended by Oliver. * Changed its name from move_init to moveinit. * Used self-modifying code in the subroutine. * The INIT segment doesn't need to be optional (it's used by the start-up file).
2015-10-07 18:56:14 +00:00
bnz L1 ; page not finished
Adapted, to the c64 target, the INIT-segment overlay scheme from the apple2 targets. When a program starts running, INIT is moved from one place to another place. Then, INIT's code is executed; and, the first place is re-used for variables. After the INIT code has finished, the second place can be re-used by the heap and the C stack. That means that initiation code and data won't waste any RAM space after they stop being needed.
2015-10-05 09:47:43 +00:00
Reduced the size of the moveinit subroutine. Made other changes that were recommended by Oliver. * Changed its name from move_init to moveinit. * Used self-modifying code in the subroutine. * The INIT segment doesn't need to be optional (it's used by the start-up file).
2015-10-07 18:56:14 +00:00
dec init_load+2
dec init_run+2
Adapted, to the c64 target, the INIT-segment overlay scheme from the apple2 targets. When a program starts running, INIT is moved from one place to another place. Then, INIT's code is executed; and, the first place is re-used for variables. After the INIT code has finished, the second place can be re-used by the heap and the C stack. That means that initiation code and data won't waste any RAM space after they stop being needed.
2015-10-05 09:47:43 +00:00
dex
bnz L1 ; move next page
rts
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