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cc65/libsrc/c64/crt0.s

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Fixed a bug git-svn-id: svn://svn.cc65.org/cc65/trunk@1618 b7a2c559-68d2-44c3-8de9-860c34a00d81
2002-11-24 11:18:24 +00:00
;
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00
; Startup code for cc65 (C64 version)
;
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
.export _exit
.export __STARTUP__ : absolute = 1 ; Mark as startup
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
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
.import initlib, donelib
Load INITBSS segment from disk. Conceptually the INITBSS segment is not initialized in any way. Therefore it makes sense to not load it from disk. However the INIT segment has to be loaded from disk and therefore moved to its run location above the INITBSS segment. The necessary move routine increases runtime RAM usage :-( Therefore we now "unnecessarily" load the INITBSS segment from disk too meaning that the INIT segment is loaded at its run location. Therefore there's no need for the move routine anymore. After all we trade disk space for (runtime) RAM space - an easy decision ;-) Notes: - The code allowing to re-run a program without re-load present so far could not have worked as far as I can see as it only avoided to re-run the move routine but still tried to re-run the code in the INIT segment that was clobbered by zeroing the BSS. Therefore I removed the code in question altogether. I'm personally not into this "dirty re-run" but if someone wants to add an actually working solution I won't block that. - INITBSS is intentionally not just merged with the DATA segment as ROM-based targets can't reuse the INIT segment for the BSS and therefore have no reason to place the INIT segment above INITBSS. - Because ROM-based targets don't copy INITBSS from the ROM (like it is done with the DATA segment) all users of INITBSS _MUST_NOT_ presume INITBSS to be initialized with zeros!
2016-02-28 18:29:37 +00:00
.import zerobss, callmain
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
.import BSOUT
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
.import __MAIN_START__, __MAIN_SIZE__ ; Linker generated
Restored the old C-stack initiation code. I had forgotten that the stack must be put below the CBM overlays.
2015-10-08 09:05:48 +00:00
.import __STACKSIZE__ ; from configure file
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
.importzp ST
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
.include "zeropage.inc"
.include "c64.inc"
Use external symbols for the CBM kernal jump table functions. This allows to emulate these functions on platforms where one or more of these functions are not available (PET, CBM-II). git-svn-id: svn://svn.cc65.org/cc65/trunk@1544 b7a2c559-68d2-44c3-8de9-860c34a00d81
2002-11-19 23:02:47 +00:00
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00
; ------------------------------------------------------------------------
* Moved the BASIC stub that calls the compiled program into it's own segment named EXEHDR. * Renamed BASICHDR to EXEHDR for the PET-II machines. * Moved the call to CHRCH in front of the code that saves the zero page, since open files are sometimes remembered in the zero page, so we need to close them before we grab a copy. git-svn-id: svn://svn.cc65.org/cc65/trunk@4507 b7a2c559-68d2-44c3-8de9-860c34a00d81
2009-12-09 12:42:24 +00:00
; Startup code
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00
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
.segment "STARTUP"
Start:
* Moved the BASIC stub that calls the compiled program into it's own segment named EXEHDR. * Renamed BASICHDR to EXEHDR for the PET-II machines. * Moved the call to CHRCH in front of the code that saves the zero page, since open files are sometimes remembered in the zero page, so we need to close them before we grab a copy. git-svn-id: svn://svn.cc65.org/cc65/trunk@4507 b7a2c559-68d2-44c3-8de9-860c34a00d81
2009-12-09 12:42:24 +00:00
Refined the comments in the target start-up files. Fixed typo errors. Made the comments consistent across all those files.
2014-08-23 18:05:36 +00:00
; Switch off the BASIC ROM.
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
lda $01
Adapted, to the c64 target, the INIT-segment overlay scheme from the apple2 targets. When a program starts running, INIT is moved from one place to another place. Then, INIT's code is executed; and, the first place is re-used for variables. After the INIT code has finished, the second place can be re-used by the heap and the C stack. That means that initiation code and data won't waste any RAM space after they stop being needed.
2015-10-05 09:47:43 +00:00
sta mmusave ; Save the memory configuration
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
and #$F8
Refined the comments in the target start-up files. Fixed typo errors. Made the comments consistent across all those files.
2014-08-23 18:05:36 +00:00
ora #$06 ; Enable Kernal+I/O, disable BASIC
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
sta $01
Fixed last fix:-) git-svn-id: svn://svn.cc65.org/cc65/trunk@1620 b7a2c559-68d2-44c3-8de9-860c34a00d81
2002-11-24 19:13:19 +00:00
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
tsx
stx spsave ; Save the system stack ptr
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00
Renamed INITBSS to INIT and INIT to ONCE. The way we want to use the INITBSS segment - and especially the fact that it won't have the type bss on all ROM based targets - means that the name INITBSS is misleading. After all INIT is the best name from my perspective as it serves several purposes and therefore needs a rather generic name. Unfortunately this means that the current INIT segment needs to be renamed too. Looking for a short (ideally 4 letter) name I came up with ONCE as it contains all code (and data) accessed only once during initialization.
2016-03-06 20:26:22 +00:00
; Save space by putting some of the start-up code in the ONCE segment,
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
; which can be re-used by the BSS segment, the heap and the C stack.
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00
Load INITBSS segment from disk. Conceptually the INITBSS segment is not initialized in any way. Therefore it makes sense to not load it from disk. However the INIT segment has to be loaded from disk and therefore moved to its run location above the INITBSS segment. The necessary move routine increases runtime RAM usage :-( Therefore we now "unnecessarily" load the INITBSS segment from disk too meaning that the INIT segment is loaded at its run location. Therefore there's no need for the move routine anymore. After all we trade disk space for (runtime) RAM space - an easy decision ;-) Notes: - The code allowing to re-run a program without re-load present so far could not have worked as far as I can see as it only avoided to re-run the move routine but still tried to re-run the code in the INIT segment that was clobbered by zeroing the BSS. Therefore I removed the code in question altogether. I'm personally not into this "dirty re-run" but if someone wants to add an actually working solution I won't block that. - INITBSS is intentionally not just merged with the DATA segment as ROM-based targets can't reuse the INIT segment for the BSS and therefore have no reason to place the INIT segment above INITBSS. - Because ROM-based targets don't copy INITBSS from the ROM (like it is done with the DATA segment) all users of INITBSS _MUST_NOT_ presume INITBSS to be initialized with zeros!
2016-02-28 18:29:37 +00:00
jsr init
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
; Clear the BSS data.
jsr zerobss
; Push the command-line arguments; and, call main().
jsr callmain
Added an interrupt facility similar to that on the C128 and Plus/4 git-svn-id: svn://svn.cc65.org/cc65/trunk@2956 b7a2c559-68d2-44c3-8de9-860c34a00d81
2004-03-23 21:50:15 +00:00
Refined the comments in the target start-up files. Fixed typo errors. Made the comments consistent across all those files.
2014-08-23 18:05:36 +00:00
; Back from main() [this is also the exit() entry]. Run the module destructors.
Added an interrupt facility similar to that on the C128 and Plus/4 git-svn-id: svn://svn.cc65.org/cc65/trunk@2956 b7a2c559-68d2-44c3-8de9-860c34a00d81
2004-03-23 21:50:15 +00:00
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
_exit: pha ; Save the return code on stack
jsr donelib
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00
Refined the comments in the target start-up files. Fixed typo errors. Made the comments consistent across all those files.
2014-08-23 18:05:36 +00:00
; Copy back the zero-page stuff.
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
ldx #zpspace-1
L2: lda zpsave,x
sta sp,x
dex
bpl L2
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00
Refined the comments in the target start-up files. Fixed typo errors. Made the comments consistent across all those files.
2014-08-23 18:05:36 +00:00
; Place the program return code into BASIC's status variable.
Place the return code into ST git-svn-id: svn://svn.cc65.org/cc65/trunk@2884 b7a2c559-68d2-44c3-8de9-860c34a00d81
2004-03-02 17:08:07 +00:00
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
pla
sta ST
Place the return code into ST git-svn-id: svn://svn.cc65.org/cc65/trunk@2884 b7a2c559-68d2-44c3-8de9-860c34a00d81
2004-03-02 17:08:07 +00:00
Refined the comments in the target start-up files. Fixed typo errors. Made the comments consistent across all those files.
2014-08-23 18:05:36 +00:00
; Restore the system stuff.
Fixed issues with the last change: The return code must be pulled from stack before the stack pointer is reset. git-svn-id: svn://svn.cc65.org/cc65/trunk@2906 b7a2c559-68d2-44c3-8de9-860c34a00d81
2004-03-08 20:38:58 +00:00
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
ldx spsave
txs ; Restore stack pointer
ldx mmusave
stx $01 ; Restore memory configuration
Fixed issues with the last change: The return code must be pulled from stack before the stack pointer is reset. git-svn-id: svn://svn.cc65.org/cc65/trunk@2906 b7a2c559-68d2-44c3-8de9-860c34a00d81
2004-03-08 20:38:58 +00:00
Refined the comments in the target start-up files. Fixed typo errors. Made the comments consistent across all those files.
2014-08-23 18:05:36 +00:00
; Back to BASIC.
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
rts
This commit was generated by cvs2svn to compensate for changes in r2, which included commits to RCS files with non-trunk default branches. git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00
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
Added LOWCODE and STARTUP segments git-svn-id: svn://svn.cc65.org/cc65/trunk@1600 b7a2c559-68d2-44c3-8de9-860c34a00d81
2002-11-22 23:50:45 +00:00
; ------------------------------------------------------------------------
Renamed INITBSS to INIT and INIT to ONCE. The way we want to use the INITBSS segment - and especially the fact that it won't have the type bss on all ROM based targets - means that the name INITBSS is misleading. After all INIT is the best name from my perspective as it serves several purposes and therefore needs a rather generic name. Unfortunately this means that the current INIT segment needs to be renamed too. Looking for a short (ideally 4 letter) name I came up with ONCE as it contains all code (and data) accessed only once during initialization.
2016-03-06 20:26:22 +00:00
.segment "ONCE"
Moved the data that keeps a copy of the used zero page locations in its own segment to reduce the executable size. git-svn-id: svn://svn.cc65.org/cc65/trunk@3849 b7a2c559-68d2-44c3-8de9-860c34a00d81
2008-07-03 19:39:14 +00:00
Load INITBSS segment from disk. Conceptually the INITBSS segment is not initialized in any way. Therefore it makes sense to not load it from disk. However the INIT segment has to be loaded from disk and therefore moved to its run location above the INITBSS segment. The necessary move routine increases runtime RAM usage :-( Therefore we now "unnecessarily" load the INITBSS segment from disk too meaning that the INIT segment is loaded at its run location. Therefore there's no need for the move routine anymore. After all we trade disk space for (runtime) RAM space - an easy decision ;-) Notes: - The code allowing to re-run a program without re-load present so far could not have worked as far as I can see as it only avoided to re-run the move routine but still tried to re-run the code in the INIT segment that was clobbered by zeroing the BSS. Therefore I removed the code in question altogether. I'm personally not into this "dirty re-run" but if someone wants to add an actually working solution I won't block that. - INITBSS is intentionally not just merged with the DATA segment as ROM-based targets can't reuse the INIT segment for the BSS and therefore have no reason to place the INIT segment above INITBSS. - Because ROM-based targets don't copy INITBSS from the ROM (like it is done with the DATA segment) all users of INITBSS _MUST_NOT_ presume INITBSS to be initialized with zeros!
2016-02-28 18:29:37 +00:00
init:
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
; Save the zero-page locations that we need.
Moved the data that keeps a copy of the used zero page locations in its own segment to reduce the executable size. git-svn-id: svn://svn.cc65.org/cc65/trunk@3849 b7a2c559-68d2-44c3-8de9-860c34a00d81
2008-07-03 19:39:14 +00:00
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
ldx #zpspace-1
L1: lda sp,x
sta zpsave,x
dex
bpl L1
; Set up the stack.
Cleaned up C64 linker configs. The BSS segment and the ONCE segment share the same start address. So they need to be placed in two different memory areas. So far BSS was placed in the MAIN memory area and ONCE was placed in an additional memory area. Both memory areas were written to the output file. They just "happened" to be loadable and runnable at a stretch. Now ONCE is placed in the MAIN memory area and BSS is placed in an additional memory area. Only MAIN is written to the output file. It becomes more obvious that BSS is "just" defined to share memory with ONCE.
2016-03-13 13:32:07 +00:00
lda #<(__MAIN_START__ + __MAIN_SIZE__)
ldx #>(__MAIN_START__ + __MAIN_SIZE__)
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
sta sp
stx sp+1 ; Set argument stack ptr
Load INITBSS segment from disk. Conceptually the INITBSS segment is not initialized in any way. Therefore it makes sense to not load it from disk. However the INIT segment has to be loaded from disk and therefore moved to its run location above the INITBSS segment. The necessary move routine increases runtime RAM usage :-( Therefore we now "unnecessarily" load the INITBSS segment from disk too meaning that the INIT segment is loaded at its run location. Therefore there's no need for the move routine anymore. After all we trade disk space for (runtime) RAM space - an easy decision ;-) Notes: - The code allowing to re-run a program without re-load present so far could not have worked as far as I can see as it only avoided to re-run the move routine but still tried to re-run the code in the INIT segment that was clobbered by zeroing the BSS. Therefore I removed the code in question altogether. I'm personally not into this "dirty re-run" but if someone wants to add an actually working solution I won't block that. - INITBSS is intentionally not just merged with the DATA segment as ROM-based targets can't reuse the INIT segment for the BSS and therefore have no reason to place the INIT segment above INITBSS. - Because ROM-based targets don't copy INITBSS from the ROM (like it is done with the DATA segment) all users of INITBSS _MUST_NOT_ presume INITBSS to be initialized with zeros!
2016-02-28 18:29:37 +00:00
; Switch to the second charset.
lda #14
jsr BSOUT
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
; Call the module constructors.
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
jmp initlib
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
; ------------------------------------------------------------------------
; Data
Renamed INITBSS to INIT and INIT to ONCE. The way we want to use the INITBSS segment - and especially the fact that it won't have the type bss on all ROM based targets - means that the name INITBSS is misleading. After all INIT is the best name from my perspective as it serves several purposes and therefore needs a rather generic name. Unfortunately this means that the current INIT segment needs to be renamed too. Looking for a short (ideally 4 letter) name I came up with ONCE as it contains all code (and data) accessed only once during initialization.
2016-03-06 20:26:22 +00:00
.segment "INIT"
Explained why two variables were moved out of the BSS segment.
2015-10-09 16:00:41 +00:00
Removed (pretty inconsistently used) tab chars from source code base.
2013-05-09 11:56:54 +00:00
mmusave:.res 1
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
spsave: .res 1
zpsave: .res zpspace
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