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sub_815A1F8

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This commit is contained in:
jiangzhengwenjz
2019-12-11 02:42:38 +08:00
parent 764b19b470
commit c609b533d4
7 changed files with 20 additions and 486 deletions
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src/battle_transition.c
+8 -48
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@@ -1599,12 +1599,7 @@ static void sub_80D1F64(s16 a1, s16 a2, u8 a3)
}
}
}
// PROBLEM #3: We need (a2 << 16) & 0x30000 here.
// Is it because the programmer declared a s32 var to
// hold the value of a2 and then cast the result to s16?
// Currently I have to write it explicitly.
// (around line 460 in ASM)
if (!a3 || !((a2 << 16) & 0x30000))
if (a3 == 0 || a2 % 4 == 0)
{
for (i = 0; i < 160; ++i)
gScanlineEffectRegBuffers[1][i * 2 + a3] = (gScanlineEffectRegBuffers[1][i + 320] << 8) | gScanlineEffectRegBuffers[1][i + 480];
@@ -1618,49 +1613,14 @@ static void sub_80D1F64(s16 a1, s16 a2, u8 a3)
case 0:
if (res > 80)
res = 80;
// PROBLEM #4:
// PROBLEM #3:
// (around line 550 in ASM)
// Case 0-3 are very similar, so it's very likely
// that they have the same problem.
// The code is definitely functional equivalent,
// but the vanilla game used some extra shifts and
// used unsigned comparison. Another difference is
// that I can't figure out a way to make gUnknown_83FA444[a2]
// happen outside the loop body.
// It seems that sTransitionStructPtr->data[2] need
// to be used in the first statement so that the
// struct pointer sTransitionStructPtr will be loaded
// early enough.
//
// Logically the generated code is following if + do-while structure.
// But it seems that it can only make the situation even worse.
/*
i = res;
if (i > 0)
{
// This happens before loop body.
s16 unk = gUnknown_83FA444[a2];
do
{
sTransitionStructPtr->data[2] = ((i * unk) >> 8) + 120;
if (sTransitionStructPtr->data[2] <= 255)
{
sTransitionStructPtr->bg123HOfs = 400 - i;
sTransitionStructPtr->data[10] = gScanlineEffectRegBuffers[1][400 - i];
if (gScanlineEffectRegBuffers[1][560 - i] < sTransitionStructPtr->data[2])
gScanlineEffectRegBuffers[1][560 - i] = 120;
else if (gScanlineEffectRegBuffers[1][400 - i] < sTransitionStructPtr->data[2])
gScanlineEffectRegBuffers[1][400 - i] = sTransitionStructPtr->data[2];
}
}
while (--i > 0);
}
*/
// Case 0 ... 3 are very similar, so it's very likely that they have the same problem.
// Weird shifts around writing to sTransitionStructPtr->data[2], and the following comparison.
for (i = res; i > 0; --i)
{
sTransitionStructPtr->data[2] = ((i * gUnknown_83FA444[a2]) >> 8) + 120;
if (sTransitionStructPtr->data[2] <= 255)
if (sTransitionStructPtr->data[2] <= 255u) // why is this unsigned?
{
sTransitionStructPtr->bg123HOfs = 400 - i;
sTransitionStructPtr->data[10] = gScanlineEffectRegBuffers[1][400 - i];
@@ -1674,7 +1634,7 @@ static void sub_80D1F64(s16 a1, s16 a2, u8 a3)
case 1:
if (res > 80)
res = 80;
// same as PROBLEM #4
// same as PROBLEM #3
for (i = res; i > 0; --i)
{
s16 unkVal;
@@ -1692,7 +1652,7 @@ static void sub_80D1F64(s16 a1, s16 a2, u8 a3)
case 2:
if (res < -79)
res = -79;
// same as PROBLEM #4
// same as PROBLEM #3
for (i = res; i <= 0; ++i)
{
sTransitionStructPtr->data[2] = ((i * gUnknown_83FA444[a2]) >> 8) + 120;
@@ -1710,7 +1670,7 @@ static void sub_80D1F64(s16 a1, s16 a2, u8 a3)
case 3:
if (res < -79)
res = -79;
// same as PROBLEM #4
// same as PROBLEM #3
for (i = res; i <= 0; ++i)
{
sTransitionStructPtr->data[2] = ((i * gUnknown_83FA444[a2]) >> 8) + 120;