56 lines
1.7 KiB
Nim
56 lines
1.7 KiB
Nim
# Stint
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# Copyright 2018 Status Research & Development GmbH
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# Licensed under either of
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#
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# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
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# * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
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#
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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import ../datatypes
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# ############################################################
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#
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# Extended precision primitives for X86-64 on GCC & Clang
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#
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# ############################################################
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static:
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doAssert(defined(gcc) or defined(clang) or defined(llvm_gcc))
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doAssert sizeof(int) == 8
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doAssert X86
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func div2n1n_128*(q, r: var uint64, n_hi, n_lo, d: uint64) {.inline.}=
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## Division uint128 by uint64
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## Warning ⚠️ :
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## - if n_hi == d, quotient does not fit in an uint64 and will throw SIGFPE
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## - if n_hi > d result is undefined
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# DIV r/m64
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# Divide RDX:RAX (n_hi:n_lo) by r/m64
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#
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# Inputs
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# - numerator high word in RDX,
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# - numerator low word in RAX,
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# - divisor as r/m parameter (register or memory at the compiler discretion)
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# Result
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# - Quotient in RAX
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# - Remainder in RDX
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# 1. name the register/memory "divisor"
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# 2. don't forget to dereference the var hidden pointer
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# 3. -
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# 4. no clobbered registers beside explicitly used RAX and RDX
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when defined(cpp):
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asm """
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divq %[divisor]
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:"=a" (`q`), "=d" (`r`)
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:"d" (`n_hi`), "a" (`n_lo`), [divisor] "rm" (`d`)
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"""
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else:
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asm """
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divq %[divisor]
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:"=a" (*`q`), "=d" (*`r`)
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:"d" (`n_hi`), "a" (`n_lo`), [divisor] "rm" (`d`)
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"""
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