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3d0m2_te: alu_calc ALU mode (result < 0) was not possible, and simplify Boolean mode (nw)

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This commit is contained in:
hap 2019-03-30 19:18:05 +01:00
parent 3226360252
commit cf5044123b
1 changed files with 5 additions and 25 deletions
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30
src/mame/video/3dom2_te.cpp
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@ -3010,10 +3010,8 @@ uint8_t m2_te_device::color_blend(uint8_t ct, uint8_t cti, uint8_t cs, uint8_t c
uint8_t m2_te_device::alu_calc(uint16_t a, uint16_t b)
{
uint16_t cinv;
uint16_t c = 0;
int32_t result = 0;
uint32_t blendout;
uint32_t result;
uint32_t carry = 0;
uint32_t borrow = 0;
uint32_t cntl = (m_db.alu_ctrl & DBALUCNTL_ALUOP_MASK) >> DBALUCNTL_ALUOP_SHIFT;
@ -3021,7 +3019,7 @@ uint8_t m2_te_device::alu_calc(uint16_t a, uint16_t b)
// p271
/* ALU */
if ((cntl & 8) == 0)
if ((cntl & 8) == 0)
{
if (!(cntl & 4))
{
@ -3043,36 +3041,18 @@ uint8_t m2_te_device::alu_calc(uint16_t a, uint16_t b)
/* Boolean */
else
{
cinv = 0;
int i, j;
for (i = 0; i < 8; ++i)
{
j = (a & 1) *2 + (b & 1);
switch (j)
{
case 0: cinv |= (cntl & 1); break;
case 1: cinv |= ((cntl & 2) != 0); break;
case 2: cinv |= ((cntl & 4) != 0); break;
case 3: cinv |= ((cntl & 8) != 0); break;
}
result >>= 1;
result |= (cntl >> j & 1) ? 0x80 : 0;
cinv <<= 1;
a >>= 1;
b >>= 1;
}
cinv >>= 1;
for (i = 0; i < 8; ++i)
{
c |= cinv & 1;
c <<= 1;
cinv >>= 1;
}
c >>= 1;
result = (int)c;
}
result &= 0x1ff;
@ -3102,7 +3082,7 @@ uint8_t m2_te_device::alu_calc(uint16_t a, uint16_t b)
alugel = 4;
#endif
if ((cntl & 8) == 0)
if ((cntl & 8) == 0)
{
/* Clamp? */
if (!(cntl & 1))