Fix Ocarina of Time frame ratio calculation and enable frame buffering (0400486024DEC000)

dm/games/0400486024DEC000/game.tsv

@@ -40,6 +40,7 @@ shader_note	Ocarina of Time shaders
 # The game steps its time by a frame ratio, its base rate / its frame rate, whatever the frame took: frames longer than a vsync played in slow motion. The ratio takes the host's
 # frame step instead (MATCH_FRAME_STEP in patches.py, found by its function on any build that keeps it): 1 vsync at 60 fps, 2 when 60 does not hold, so game time = real time
 fps_target	60
+present_snap	on
 
 # ---- Graphics ----
 # agl wraps its clears in render conditions on Donkey Kong Bananza and Splatoon Raiders; the same library here

dm/games/0400486024DEC000/patches.py

@@ -4,8 +4,8 @@
 
 # The game's frame ratio. Once a frame the function at main+0x6e6be0 (v131072) divides its base rate (60.0, or 30.0 while bit 0 of [x21+0x24f] is set) by the int frame rate at
 # [x21+0x2c8] (fdiv s8,s1,s0 at +0xe4) and hands the result to the time object (main+0x3b4e300: ratio at +0x10, 1 / ratio at +0x14, round(60 / ratio) at +0x1c), which the game
-# steps by; the frame's own time never enters it, so a frame that takes two vsyncs at rate 60 plays at half speed. The stub gives the ratio the host's step instead: step × base / 60
-# (the division's value when the host keeps frames 60 / rate vsyncs), and counts the vsyncs stepped. Until the host has decided a step, and at fps_target 0, the division runs.
+# steps by; the frame's own time never enters it, so a frame that takes two vsyncs at rate 60 plays at half speed. The stub gives the ratio the host's step instead: (float)step
+# (the ratio when the host keeps frames 60 / rate vsyncs), and counts the vsyncs stepped. Until the host has decided a step, and at fps_target 0, the division runs.
 # s0 and x16 / x17 are free there (s0 is written again on every path before it is read; the function uses neither x16 nor x17); s1 keeps the base rate.
 # Lichii (a GPL emulator; only the fact was taken) found the division (its notes: main+0x6E6CC4, 60 / [x21+0x2C8])
 def frame_step(ctx):
@@ -14,23 +14,20 @@ def frame_step(ctx):
     fs_site(site, '2818201e')   # fdiv s8,s1,s0
     start = here(); emit(ADRP(16, here(), FS_STATE_OFF))
     for w in (0xb9400211,   # ldr w17,[x16]          target fps (0 = off)
-              0x340001b1,   # cbz w17,orig (+13)
+              0x34000151,   # cbz w17,orig (+10)
               0xb9402211,   # ldr w17,[x16,#0x20]    step in vsyncs
-              0x34000171,   # cbz w17,orig (+11)     not decided yet
+              0x34000111,   # cbz w17,orig (+8)      not decided yet
               0x1e230220,   # ucvtf s0,w17
               0xf9401a10,   # ldr x16,[x16,#0x30]
               0x8b110210):  # add x16,x16,x17
         emit(w)
     emit(ADRP(17, here(), FS_STATE_OFF))
     for w in (0xf9001a30,   # str x16,[x17,#0x30]    vsyncs stepped
-              0x1e210808,   # fmul s8,s0,s1          step × base rate
-              0x52a84e10,   # mov w16,#0x42700000    60.0
-              0x1e270200,   # fmov s0,w16
-              0x1e201908):  # fdiv s8,s8,s0          / 60
+              0x1e204008):  # fmov s8,s0             step as ratio
         emit(w)
     emit(B(here(), site + 4))
     emit(0x1e201828); emit(B(here(), site + 4))   # orig: fdiv s8,s1,s0; back
-    fs_put(site, [B(site, start)], 'frame ratio: the host\'s step × base rate / 60 instead of base rate / the game\'s frame rate (state page target fps; 0 = the game\'s ratio)')
+    fs_put(site, [B(site, start)], 'frame ratio: the host\'s step instead of base rate / the game\'s frame rate (state page target fps; 0 = the game\'s ratio)')
     dynamic_resolution(ctx)
 
 # The game's dynamic resolution (game__gfx__DynamicResolutionParam: LoadThreshold, ReduceCounterMax, IncreaseCounterMax and a list of levels, each a ResolutionReduceScale and a