Sprintf decimal formatting inconsistent with other emulators

[jackbonaguro]

I wrote a small program using tonc that just displays the string resulting from sprintf(str, "should print \"-1\": %d\n", -1);. The resulting GBA file faithfully prints should print "-1": -1 on mGBA on mac, PizzaBoy on Android, and SkyEmu in browser; but for gba.js.org, it prints should print "-1": -4294967297.

-4294967297 is 0x100000001 in hex; I would expect 0xffffffff instead. If I change the format string from %d to %x, all emulators print 0xffffffff. To me this indicates that the affected code is in sprintf, but the bug is in the emulator as an identical sprintf version is compiled into the same .gba file that results in different behavior per emulator.

Screenshots:

SkyEmu (web.skyemu.app):

GBA.JS.ORG:

main.c:

#include <string.h>
#include <tonc.h>

void update_console() {
	tte_erase_screen();
	tte_write("#{P:1,1}");
	char str[48];
	sprintf(str, "should print \"-1\": %d\n", -1);
	tte_write(str);
}

int main() {
	REG_DISPCNT= DCNT_OBJ | DCNT_OBJ_1D;
	REG_DISPCNT = REG_DISPCNT | DCNT_MODE0 | DCNT_BG0 | DCNT_BG1;
	REG_BGCNT[1]= BG_CBB(1) | BG_SBB(31) | BG_4BPP | BG_REG_32x32;

	tte_init_se(1, (BG_CBB(1))|BG_SBB(31), 0, CLR_YELLOW, 14, NULL, NULL);

	/* Main Loop */
	while(1) {
		vid_vsync();
		update_console();
	}

	return 0;
}

Attached .zip file includes sources and built .gba file. Depends on a working devkitPro toolchain to build from source.

gba-test.zip

[ayvacs]

yeah i got no clue sorry bro