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Performs a first implementation of fill mode.

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This commit is contained in:
Thomas Harte 2021-10-31 14:36:31 -07:00
parent 561e73dbd7
commit 299d517449
1 changed files with 30 additions and 6 deletions
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36
Machines/Amiga/Blitter.cpp
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@ -29,8 +29,8 @@ void Blitter::set_control(int index, uint16_t value) {
line_sign_ = (value & 0x0040) ? -1 : 1;
direction_ = one_dot_ ? uint32_t(-1) : uint32_t(1);
inclusive_fill_ = (value & 0x0008);
exclusive_fill_ = (value & 0x0010);
inclusive_fill_ = (value & 0x0008);
fill_carry_ = (value & 0x0004);
} else {
minterms_ = value & 0xff;
@ -208,10 +208,6 @@ bool Blitter::advance() {
}
}
} else {
// As-yet unimplemented:
assert(!inclusive_fill_);
assert(!exclusive_fill_);
// Copy mode.
// Quick hack: do the entire action atomically.
@ -219,6 +215,8 @@ bool Blitter::advance() {
b32_ = 0;
for(int y = 0; y < height_; y++) {
bool fill_carry = fill_carry_;
for(int x = 0; x < width_; x++) {
uint16_t a_mask = 0xffff;
if(x == 0) a_mask &= a_mask_[0];
@ -261,12 +259,38 @@ bool Blitter::advance() {
);
}
const uint16_t output =
uint16_t output =
apply_minterm<uint16_t>(
a,
b,
c_data_,
minterms_);
// TODO: don't be so dense as below. This is the initial
// does-it-pass-the-tests? version.
if(exclusive_fill_ || inclusive_fill_) {
uint16_t fill_output = 0;
uint16_t bit = one_dot_ ? 0x0001 : 0x8000;
uint16_t flag = fill_carry ? bit : 0x0000;
while(bit) {
if(exclusive_fill_) flag ^= (output & bit);
if(inclusive_fill_) flag ^= (output & bit & ~flag); // Accept bits that would transition to set immediately.
fill_output |= flag;
if(inclusive_fill_) flag ^= (output & bit & flag); // Accept bits that would transition to clear after the fact.
fill_carry = flag;
if(one_dot_) {
bit <<= 1;
flag <<= 1;
} else {
bit >>= 1;
flag >>= 1;
}
}
output = fill_output;
}
not_zero_flag_ |= output;
if(channel_enables_[3]) {