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Merge pull request #1002 from TomHarte/FastBlitterFills
Switch to a table-based implementation of fill mode.
This commit is contained in:
Thomas Harte
GitHub
commit
bdf0a1941c
@ -21,6 +21,98 @@
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using namespace Amiga;
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namespace {
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/// @returns Either the final carry flag or the output nibble when using fill mode given that it either @c is_exclusive fill mode, or isn't;
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/// and the specified initial @c carry and input @c nibble.
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template <bool wants_carry> constexpr uint32_t fill_nibble(bool is_exclusive, uint8_t carry, uint8_t nibble) {
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uint8_t fill_output = 0;
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uint8_t bit = 0x01;
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while(bit < 0x10) {
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auto pre_toggle = nibble & bit, post_toggle = pre_toggle;
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if(!is_exclusive) {
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pre_toggle &= ~carry; // Accept bits that would transition to set immediately.
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post_toggle &= carry; // Accept bits that would transition to clear after the fact.
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} else {
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post_toggle = 0; // Just do the pre-toggle.
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}
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carry ^= pre_toggle;
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fill_output |= carry;
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carry ^= post_toggle;
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bit <<= 1;
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carry <<= 1;
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}
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if constexpr (wants_carry) {
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return carry >> 4;
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} else {
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return fill_output;
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}
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}
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// Lookup key for these tables is:
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//
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// b0–b3: input nibble
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// b4: carry
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// b5: is_exclusive
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//
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// i.e. it's in the range [0, 63].
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//
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// Tables below are indexed such that the higher-order bits select a table entry, lower-order bits select
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// a bit or nibble from within the indexed item.
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constexpr uint32_t fill_carries[] = {
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(fill_nibble<true>(false, 0, 0x0) << 0x0) | (fill_nibble<true>(false, 0, 0x1) << 0x1) | (fill_nibble<true>(false, 0, 0x2) << 0x2) | (fill_nibble<true>(false, 0, 0x3) << 0x3) |
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(fill_nibble<true>(false, 0, 0x4) << 0x4) | (fill_nibble<true>(false, 0, 0x5) << 0x5) | (fill_nibble<true>(false, 0, 0x6) << 0x6) | (fill_nibble<true>(false, 0, 0x7) << 0x7) |
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(fill_nibble<true>(false, 0, 0x8) << 0x8) | (fill_nibble<true>(false, 0, 0x9) << 0x9) | (fill_nibble<true>(false, 0, 0xa) << 0xa) | (fill_nibble<true>(false, 0, 0xb) << 0xb) |
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(fill_nibble<true>(false, 0, 0xc) << 0xc) | (fill_nibble<true>(false, 0, 0xd) << 0xd) | (fill_nibble<true>(false, 0, 0xe) << 0xe) | (fill_nibble<true>(false, 0, 0xf) << 0xf) |
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(fill_nibble<true>(false, 1, 0x0) << 0x10) | (fill_nibble<true>(false, 1, 0x1) << 0x11) | (fill_nibble<true>(false, 1, 0x2) << 0x12) | (fill_nibble<true>(false, 1, 0x3) << 0x13) |
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(fill_nibble<true>(false, 1, 0x4) << 0x14) | (fill_nibble<true>(false, 1, 0x5) << 0x15) | (fill_nibble<true>(false, 1, 0x6) << 0x16) | (fill_nibble<true>(false, 1, 0x7) << 0x17) |
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(fill_nibble<true>(false, 1, 0x8) << 0x18) | (fill_nibble<true>(false, 1, 0x9) << 0x19) | (fill_nibble<true>(false, 1, 0xa) << 0x1a) | (fill_nibble<true>(false, 1, 0xb) << 0x1b) |
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(fill_nibble<true>(false, 1, 0xc) << 0x1c) | (fill_nibble<true>(false, 1, 0xd) << 0x1d) | (fill_nibble<true>(false, 1, 0xe) << 0x1e) | (fill_nibble<true>(false, 1, 0xf) << 0x1f),
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(fill_nibble<true>(true, 0, 0x0) << 0x0) | (fill_nibble<true>(true, 0, 0x1) << 0x1) | (fill_nibble<true>(true, 0, 0x2) << 0x2) | (fill_nibble<true>(true, 0, 0x3) << 0x3) |
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(fill_nibble<true>(true, 0, 0x4) << 0x4) | (fill_nibble<true>(true, 0, 0x5) << 0x5) | (fill_nibble<true>(true, 0, 0x6) << 0x6) | (fill_nibble<true>(true, 0, 0x7) << 0x7) |
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(fill_nibble<true>(true, 0, 0x8) << 0x8) | (fill_nibble<true>(true, 0, 0x9) << 0x9) | (fill_nibble<true>(true, 0, 0xa) << 0xa) | (fill_nibble<true>(true, 0, 0xb) << 0xb) |
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(fill_nibble<true>(true, 0, 0xc) << 0xc) | (fill_nibble<true>(true, 0, 0xd) << 0xd) | (fill_nibble<true>(true, 0, 0xe) << 0xe) | (fill_nibble<true>(true, 0, 0xf) << 0xf) |
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(fill_nibble<true>(true, 1, 0x0) << 0x10) | (fill_nibble<true>(true, 1, 0x1) << 0x11) | (fill_nibble<true>(true, 1, 0x2) << 0x12) | (fill_nibble<true>(true, 1, 0x3) << 0x13) |
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(fill_nibble<true>(true, 1, 0x4) << 0x14) | (fill_nibble<true>(true, 1, 0x5) << 0x15) | (fill_nibble<true>(true, 1, 0x6) << 0x16) | (fill_nibble<true>(true, 1, 0x7) << 0x17) |
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(fill_nibble<true>(true, 1, 0x8) << 0x18) | (fill_nibble<true>(true, 1, 0x9) << 0x19) | (fill_nibble<true>(true, 1, 0xa) << 0x1a) | (fill_nibble<true>(true, 1, 0xb) << 0x1b) |
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(fill_nibble<true>(true, 1, 0xc) << 0x1c) | (fill_nibble<true>(true, 1, 0xd) << 0x1d) | (fill_nibble<true>(true, 1, 0xe) << 0x1e) | (fill_nibble<true>(true, 1, 0xf) << 0x1f),
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};
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constexpr uint32_t fill_values[] = {
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(fill_nibble<false>(false, 0, 0x0) << 0) | (fill_nibble<false>(false, 0, 0x1) << 4) | (fill_nibble<false>(false, 0, 0x2) << 8) | (fill_nibble<false>(false, 0, 0x3) << 12) |
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(fill_nibble<false>(false, 0, 0x4) << 16) | (fill_nibble<false>(false, 0, 0x5) << 20) | (fill_nibble<false>(false, 0, 0x6) << 24) | (fill_nibble<false>(false, 0, 0x7) << 28),
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(fill_nibble<false>(false, 0, 0x8) << 0) | (fill_nibble<false>(false, 0, 0x9) << 4) | (fill_nibble<false>(false, 0, 0xa) << 8) | (fill_nibble<false>(false, 0, 0xb) << 12) |
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(fill_nibble<false>(false, 0, 0xc) << 16) | (fill_nibble<false>(false, 0, 0xd) << 20) | (fill_nibble<false>(false, 0, 0xe) << 24) | (fill_nibble<false>(false, 0, 0xf) << 28),
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(fill_nibble<false>(false, 1, 0x0) << 0) | (fill_nibble<false>(false, 1, 0x1) << 4) | (fill_nibble<false>(false, 1, 0x2) << 8) | (fill_nibble<false>(false, 1, 0x3) << 12) |
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(fill_nibble<false>(false, 1, 0x4) << 16) | (fill_nibble<false>(false, 1, 0x5) << 20) | (fill_nibble<false>(false, 1, 0x6) << 24) | (fill_nibble<false>(false, 1, 0x7) << 28),
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(fill_nibble<false>(false, 1, 0x8) << 0) | (fill_nibble<false>(false, 1, 0x9) << 4) | (fill_nibble<false>(false, 1, 0xa) << 8) | (fill_nibble<false>(false, 1, 0xb) << 12) |
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(fill_nibble<false>(false, 1, 0xc) << 16) | (fill_nibble<false>(false, 1, 0xd) << 20) | (fill_nibble<false>(false, 1, 0xe) << 24) | (fill_nibble<false>(false, 1, 0xf) << 28),
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(fill_nibble<false>(true, 0, 0x0) << 0) | (fill_nibble<false>(true, 0, 0x1) << 4) | (fill_nibble<false>(true, 0, 0x2) << 8) | (fill_nibble<false>(true, 0, 0x3) << 12) |
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(fill_nibble<false>(true, 0, 0x4) << 16) | (fill_nibble<false>(true, 0, 0x5) << 20) | (fill_nibble<false>(true, 0, 0x6) << 24) | (fill_nibble<false>(true, 0, 0x7) << 28),
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(fill_nibble<false>(true, 0, 0x8) << 0) | (fill_nibble<false>(true, 0, 0x9) << 4) | (fill_nibble<false>(true, 0, 0xa) << 8) | (fill_nibble<false>(true, 0, 0xb) << 12) |
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(fill_nibble<false>(true, 0, 0xc) << 16) | (fill_nibble<false>(true, 0, 0xd) << 20) | (fill_nibble<false>(true, 0, 0xe) << 24) | (fill_nibble<false>(true, 0, 0xf) << 28),
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(fill_nibble<false>(true, 1, 0x0) << 0) | (fill_nibble<false>(true, 1, 0x1) << 4) | (fill_nibble<false>(true, 1, 0x2) << 8) | (fill_nibble<false>(true, 1, 0x3) << 12) |
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(fill_nibble<false>(true, 1, 0x4) << 16) | (fill_nibble<false>(true, 1, 0x5) << 20) | (fill_nibble<false>(true, 1, 0x6) << 24) | (fill_nibble<false>(true, 1, 0x7) << 28),
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(fill_nibble<false>(true, 1, 0x8) << 0) | (fill_nibble<false>(true, 1, 0x9) << 4) | (fill_nibble<false>(true, 1, 0xa) << 8) | (fill_nibble<false>(true, 1, 0xb) << 12) |
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(fill_nibble<false>(true, 1, 0xc) << 16) | (fill_nibble<false>(true, 1, 0xd) << 20) | (fill_nibble<false>(true, 1, 0xe) << 24) | (fill_nibble<false>(true, 1, 0xf) << 28),
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};
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}
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void Blitter::set_control(int index, uint16_t value) {
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if(index) {
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line_mode_ = (value & 0x0001);
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@ -270,36 +362,20 @@ bool Blitter::advance_dma() {
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c_data_,
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minterms_);
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// TODO: don't be so dense as below. This is the initial
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// does-it-pass-the-tests? version.
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if(exclusive_fill_ || inclusive_fill_) {
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// Use the fill tables nibble-by-nibble to figure out the filled word.
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uint16_t fill_output = 0;
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uint16_t bit = one_dot_ ? 0x0001 : 0x8000;
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uint16_t flag = fill_carry ? bit : 0x0000;
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while(bit) {
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uint16_t pre_toggle = output & bit, post_toggle = pre_toggle;
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if(inclusive_fill_) {
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pre_toggle &= ~flag; // Accept bits that would transition to set immediately.
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post_toggle &= flag; // Accept bits that would transition to clear after the fact.
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} else {
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post_toggle = 0; // Just do the pre toggle.
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}
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flag ^= pre_toggle;
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fill_output |= flag;
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flag ^= post_toggle;
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fill_carry = flag;
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if(one_dot_) {
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bit <<= 1;
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flag <<= 1;
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} else {
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bit >>= 1;
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flag >>= 1;
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}
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int ongoing_carry = fill_carry;
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const int type_mask = exclusive_fill_ ? (1 << 5) : 0;
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for(int c = 0; c < 16; c += 4) {
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const int total_index = (output & 0xf) | (ongoing_carry << 4) | type_mask;
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fill_output |= ((fill_values[total_index >> 3] >> ((total_index & 7) * 4)) & 0xf) << c;
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ongoing_carry = (fill_carries[total_index >> 5] >> (total_index & 31)) & 1;
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output >>= 4;
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}
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output = fill_output;
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fill_carry = ongoing_carry;
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}
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not_zero_flag_ |= output;
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