mirror of
https://github.com/dingusdev/dingusppc.git
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6f0d3b48ba
Fixed an issue where TBR doesn't have full 64-bit range. The original calculation was 64 bit and ended with a ÷ 10^9. This means the max for the upper 32 bits is 2^32/10^9 = 4. The solution is to use a multiplication method that supports a 96 bit product. core/mathutils.h contains functions for that. TBR driving frequency is assumed to be less than 1 GHz. Some minor modification is required for future > 1 GHz support.
50 lines
1.5 KiB
C
50 lines
1.5 KiB
C
/*
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DingusPPC - The Experimental PowerPC Macintosh emulator
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Copyright (C) 2018-22 divingkatae and maximum
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(theweirdo) spatium
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(Contact divingkatae#1017 or powermax#2286 on Discord for more info)
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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#ifndef MATH_UTILS_H
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#define MATH_UTILS_H
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inline void _u32xu64(uint32_t a, uint64_t b, uint32_t &hi, uint64_t &lo)
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{
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uint64_t p0 = (b & 0xffffffff) * a;
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uint64_t p1 = (b >> 32) * a;
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lo = p0 + (p1 << 32);
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hi = (p1 >> 32) + (lo < p0);
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}
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inline void _u32xu64(uint32_t a, uint64_t b, uint64_t &hi, uint32_t &lo)
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{
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uint64_t p0 = (b & 0xffffffff) * a;
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uint64_t p1 = (b >> 32) * a;
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lo = p0;
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hi = (p0 >> 32) + p1;
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}
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inline void _u64xu64(uint64_t a, uint64_t b, uint64_t &hi, uint64_t &lo)
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{
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uint32_t p0h; uint64_t p0l; _u32xu64(b, a, p0h, p0l);
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uint64_t p1h; uint32_t p1l; _u32xu64(b >> 32, a, p1h, p1l);
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lo = p0l + ((uint64_t)p1l << 32);
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hi = p0h + p1h + (lo < p0l);
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}
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#endif // MATH_UTILS_H
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