Reference ยท Engine

Boot, main and the start-up calls

partialfrom#3

CoversUS SLUS_006.50:0x800977e8US SLUS_006.50:0x800185f8US SLUS_006.50:0x800193fcUS SLUS_006.50:0x80019630

crt0 (_start, 0x800977e8)

PsyQ's: zeroes 0x800c4910 .. 0x800eafb0 (bss), sets sp from the word at 0x800c3f34 less 8, gp = 0x800c3e80, InitHeap(0x800eafb0 + 4, top - stack size - bss end) with the stack size at 0x800c3f38, then main.

main (0x800185f8)

game_init()                        0x800193fc
...                                sound, display, the state block
copy 328 bytes 0x800b27d8 -> 0x800c5678   the game state's initial values
0x80019a3c(498 = DB00/CHARACTR.RAW, sp+16), 0x800219d8(result) ...
loop on mode = gp+16 (0x800c3e90):
  -1   -> 0x80030158(-1) picks the next mode (front end)
  25 in activity play -> 0x80096a30()
  < 254 -> 0x80017c0c(mode) runs a database
  else -> 0x8007475c(mode >> 8)

It prints "Activation of normal play mode" or "...activity play mode" by the byte at 0x800c5699 (0 normal, 1 activity).

game_init (0x800193fc)

  1. ORs bit 0, bit 20 and bit 15 into words at 0x8009f2f8, 0x8009f870 and 0x8009fc70 (inside the library's code range; what they are is open).
  2. 0x80021a2c; clears the scratchpad's last 1 KB from 0x1f8003fc down.
  3. 0x8001a0e4; cd_init (0x80019630): CdRemove, _96_init, CdInit, CdReadyCallback(0), CdSyncCallback(0), CdControl(Setmode, 0x80: double speed).
  4. libetc's interface call at 0x8009b168; 0x80072730 (memory card); 0x8001beb8.
  5. VSyncCallback(0x800192b4).
  6. Root counter 0xf2000001 set to 0xffff, mode 0x1000, started.
  7. 0x8001de38, 0x8006e7e8, 0x80021e40, VSync(0), 0x8002ed80.

The frame

0x8001d00c ends a frame: it finishes the drawing (0x8001d2b0, 0x8001d34c), and either swaps at once (0x8001ce0c, when the byte at gp+0xa8 is set) or sets bit 1 of the flag byte gp+0x84 (0x800c3f04) with a 20-frame time-out at gp+0x85. The vertical-blank side (0x8001d0d8, through the VSync callback) does the swap once DrawSync(1) reports the GPU idle and clears the bit; 0x8001d3c4 polls it.

Unknown

  • What the patched words at 0x8009f2f8, 0x8009f870 and 0x8009fc70 are.
  • The modes main dispatches: what 0x80030158, 0x80017c0c and 0x8007475c run.