mirror of https://github.com/ncroxon/gnu-efi
200 lines
3.8 KiB
C
200 lines
3.8 KiB
C
/*++
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Copyright (c) 1998 Intel Corporation
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Module Name:
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math.c
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Abstract:
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Revision History
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--*/
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#include "lib.h"
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//
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// Declare runtime functions
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//
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#ifdef RUNTIME_CODE
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#ifndef __GNUC__
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#pragma RUNTIME_CODE(LShiftU64)
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#pragma RUNTIME_CODE(RShiftU64)
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#pragma RUNTIME_CODE(MultU64x32)
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#pragma RUNTIME_CODE(DivU64x32)
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#endif
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#endif
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//
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//
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//
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UINT64
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LShiftU64 (
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IN UINT64 Operand,
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IN UINTN Count
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)
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// Left shift 64bit by 32bit and get a 64bit result
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{
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#ifdef __GNUC__
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return Operand << Count;
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#else
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UINT64 Result;
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_asm {
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mov eax, dword ptr Operand[0]
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mov edx, dword ptr Operand[4]
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mov ecx, Count
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and ecx, 63
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shld edx, eax, cl
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shl eax, cl
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cmp ecx, 32
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jc short ls10
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mov edx, eax
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xor eax, eax
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ls10:
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mov dword ptr Result[0], eax
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mov dword ptr Result[4], edx
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}
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return Result;
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#endif
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}
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UINT64
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RShiftU64 (
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IN UINT64 Operand,
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IN UINTN Count
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)
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// Right shift 64bit by 32bit and get a 64bit result
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{
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#ifdef __GNUC__
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return Operand >> Count;
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#else
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UINT64 Result;
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_asm {
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mov eax, dword ptr Operand[0]
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mov edx, dword ptr Operand[4]
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mov ecx, Count
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and ecx, 63
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shrd eax, edx, cl
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shr edx, cl
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cmp ecx, 32
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jc short rs10
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mov eax, edx
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xor edx, edx
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rs10:
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mov dword ptr Result[0], eax
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mov dword ptr Result[4], edx
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}
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return Result;
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#endif
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}
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UINT64
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MultU64x32 (
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IN UINT64 Multiplicand,
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IN UINTN Multiplier
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)
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// Multiple 64bit by 32bit and get a 64bit result
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{
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#ifdef __GNUC__
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return Multiplicand * Multiplier;
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#else
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UINT64 Result;
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_asm {
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mov eax, dword ptr Multiplicand[0]
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mul Multiplier
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mov dword ptr Result[0], eax
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mov dword ptr Result[4], edx
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mov eax, dword ptr Multiplicand[4]
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mul Multiplier
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add dword ptr Result[4], eax
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}
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return Result;
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#endif
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}
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UINT64
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DivU64x32 (
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IN UINT64 Dividend,
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IN UINTN Divisor,
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OUT UINTN *Remainder OPTIONAL
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)
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// divide 64bit by 32bit and get a 64bit result
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// N.B. only works for 31bit divisors!!
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{
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#if 0 && defined(__GNUC__) && !defined(__MINGW32__)
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if (Remainder)
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*Remainder = Dividend % Divisor;
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return Dividend / Divisor;
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#else
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UINT32 Rem;
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UINT32 bit;
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ASSERT (Divisor != 0);
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ASSERT ((Divisor >> 31) == 0);
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//
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// For each bit in the dividend
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//
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Rem = 0;
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for (bit=0; bit < 64; bit++) {
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#if defined(__GNUC__) || defined(__MINGW32__)
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__asm__ (
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"shll $1, %0\n\t"
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"rcll $1, 4%0\n\t"
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"rcll $1, %2\n\t"
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"mov %2, %%eax\n\t"
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"cmp %1, %%eax\n\t"
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"cmc\n\t"
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"sbb %%eax, %%eax\n\t"
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"sub %%eax, %0\n\t"
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"and %1, %%eax\n\t"
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"sub %%eax, %2"
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: /* no outputs */
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: "m"(Dividend), "m"(Divisor), "m"(Rem)
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: "cc","memory","%eax"
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);
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#else
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_asm {
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shl dword ptr Dividend[0], 1 ; shift rem:dividend left one
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rcl dword ptr Dividend[4], 1
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rcl dword ptr Rem, 1
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mov eax, Rem
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cmp eax, Divisor ; Is Rem >= Divisor?
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cmc ; No - do nothing
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sbb eax, eax ; Else,
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sub dword ptr Dividend[0], eax ; set low bit in dividen
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and eax, Divisor ; and
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sub Rem, eax ; subtract divisor
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}
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#endif
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}
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if (Remainder) {
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*Remainder = Rem;
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}
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return Dividend;
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#endif
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}
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