Migrating to new GBDK Versions

This section contains information that may be useful to know or important when upgrading to a newer GBDK release.

GBDK-2020 versions

Porting to GBDK-2020 4.2

• GBDK now requires SDCC 4.3 or higher with GBDK-2020 patches for the the z80 linker
• The following new functions replace old ones. The old functions will continue to work for now, but migration to new versions is strongly encouraged.
  • vsync(): replaces wait_vbl_done()
  • set_default_palette(): replaces cgb_compatibility()
  • move_metasprite_flipy(): replaces move_metasprite_hflip()
  • move_metasprite_flipx(): replaces move_metasprite_vflip()
  • move_metasprite_flipxy(): replaces move_metasprite_hvflip()
  • move_metasprite_ex(): replaces move_metasprite()

Porting to GBDK-2020 4.1.1

• No significant changes required

Porting to GBDK-2020 4.1.0

• GBDK now requires SDCC 4.2 or higher with GBDK-2020 patches for the the z80 linker
• The default calling convention changed in SDCC 4.2, see Calling Conventions for more details.
  • If you are linking to libraries compiled with an older version of SDCC / GBDK then you may have to recompile them.
  • If there are existing functions written in ASM which receive parameters they should also be reviewed to make sure they work with the new __sdcccall(1) calling convention, or have their header declaration changed to use OLDCALL.
  • If there are existing functions written in ASM which call other functions written in C the callee C function should be declared OLDCALL.
  • Function pointer declarations should be checked to see if they need OLDCALL added to the declaration.
    • Example (add OLDCALL at the end)
    • FROM: typedef void (*someFunc)(uint8_t, uint8_t);
    • TO: typedef void (*someFunc)(uint8_t, uint8_t) OLDCALL;
  • If you are using tools such as rgb2sdas (from hUGETracker/Driver) you may need to edit the resulting .o file and replace -mgbz80 with -msm83 in addition to using OLDCALL
• The SDCC PORT name for the Game Boy and related clones changed from gbz80 to sm83.
  • Additional details in the Console Port and Platform Settings section and FAQ entry. lcc will error out if the old PORT name is passed in.
• The library base path changed from lib/small/asxxxx/ to lib/.
  • For example lib/small/asxxxx/gb becomes lib/gb
• Allocations for ISR chain lengths were fixed.
  • Now they are VBL: 4 user handlers, LCD: 3 user handlers, SIO/TIM/JOY: 4 user handlers

Porting to GBDK-2020 4.0.6

• Renamed bgb_emu.h to emu_debug.h and BGB_* functions to EMU_*
  • Aliases for the BGB_* ones and a bgb_emu.h shim are present for backward compatibility, but updating to the new naming is recommended

Porting to GBDK-2020 4.0.5

• GBDK now requires SDCC 12259 or higher with GBDK-2020 patches
• Variables in static storage are now initialized to zero per C standard (but remaining WRAM is not cleared)
• png2asset is the new name for the png2mtspr utility
• lcc : Changed default output format when not specified from .ihx to .gb (or other active rom extension)
• The _BSS area is deprecated (use _DATA instead)
• The _BASE area is renamed to _HOME
• Variables in static storage are now initialized to zero per C standard (but remaining WRAM is not cleared)
• itoa(), uitoa(), ltoa(), ultoa() all now require a radix value (base) argument to be passed. On the Game Boy and Analogue Pocket the parameter is required but not utilized.
• set_bkg_1bit_data has been renamed to set_bkg_1bpp_data
• The following header files which are now cross platform were moved from gb/ to gbdk/: bcd.h, console.h, far_ptr.h, font.h, gbdecompress.h, gbdk-lib.h, incbin.h, metasprites.h, platform.h, version.h
  • When including them use #include <gbdk/...> instead of #include <gb/>

Porting to GBDK-2020 4.0.4

• GBDK now requires SDCC 12238 or higher
• Made sample.h, cgb.h and sgb.h independent from gb.h

Porting to GBDK-2020 4.0.3

• No significant changes required

Porting to GBDK-2020 4.0.2

• The default font has been reduced from 256 to 96 characters.
  • Code using special characters may need to be updated.
  • The off-by-1 character index offset was removed for fonts. Old fonts with the offset need to be re-adjusted.

Porting to GBDK-2020 4.0.1

• Important! : The WRAM memory region is no longer automatically initialized to zeros during startup.
  • Any variables which are declared without being initialized may have indeterminate values instead of 0 on startup. This might reveal previously hidden bugs in your code.
  • Check your code for variables that are not initialized before use.
  • In BGB you can turn on triggering exceptions (options panel) reading from unitialized RAM. This allows for some additional runtime detection of uninitialized vars.
• In .ihx files, multiple writes to the same ROM address are now warned about using ihxcheck.
• set_*_tiles() now wrap maps around horizontal and vertical boundaries correctly. Code relying on it not wrapping correctly may be affected.

Porting to GBDK-2020 4.0

• GBDK now requires SDCC 4.0.3 or higher
• The old linker link-gbz80 has been REMOVED, the linker sdldgb from SDCC is used.
  • Due to the linker change, there are no longer warnings about multiple writes to the same ROM address.
• GBDK now generates .ihx files, those are converted to a ROM using makebin (lcc can do this automatically in some use cases)
• Setting ROM bytes directly with -Wl-yp0x<address>=0x<value> is no longer supported. Instead use makebin flags. For example, use -Wm-yC instead of -Wl-yp0x143=0xC0. See faq_gb_type_header_setting.
• OAM symbol has been renamed to _shadow_OAM, that allows accessing shadow OAM directly from C code

Porting to GBDK-2020 3.2

• No significant changes required

Porting to GBDK-2020 3.1.1

• No significant changes required

Porting to GBDK-2020 3.1

• Behavior formerly enabled by USE_SFR_FOR_REG is on by default now (no need to specify it, it isn't a tested #ifdef anymore). check here why: https://gbdev.gg8.se/forums/viewtopic.php?id=697

Porting to GBDK-2020 3.0.1

• LCC was upgraded to use SDCC v4.0. Makefile changes may be required
  • The symbol format changed. To get bgb compatible symbols turn on .noi output (LCC argument: -Wl-j or -debug) and use -Wm-yS
  • ?? Suggested: With LCC argument: -Wa-l (sdasgb:-a All user symbols made global)
  • In SDCC 3.6.0, the default for char changed from signed to unsigned.
    • If you want the old behavior use --fsigned-char.
    • lcc includes --fsigned-char by default
    • Explicit declaration of unsigned vars is encouraged (for example, '15U' instead of '15')
  • .init address has been removed

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Historical GBDK versions

GBDK 1.1 to GBDK 2.0

• Change your int variables to long if they have to be bigger than 255. If they should only contain values between 0 and 255, use an unsigned int.
• If your application uses the delay function, you'll have to adapt your delay values.
• Several functions have new names. In particular some of them have been changed to macros (e.g. show_bkg() is now SHOW_BKG).
• You will probably have to change the name of the header files that you include.