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66 lines
1.5 KiB
ArmAsm
66 lines
1.5 KiB
ArmAsm
/*
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* COPYRIGHT: See COPYING in the top level directory
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* PROJECT: ReactOS system libraries
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* PURPOSE: Implementation of sqrt
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* FILE: lib/sdk/crt/math/amd64/sqrt.S
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* PROGRAMMER: Timo Kreuzer (timo.kreuzer@reactos.org)
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*/
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/* INCLUDES ******************************************************************/
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#include <asm.inc>
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/* CODE **********************************************************************/
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.code64
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PUBLIC sqrt
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sqrt:
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/* Load the sign bit into rdx */
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mov rdx, HEX(8000000000000000)
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/* Move the lower 64 bits of xmm0 into rax */
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movd rax, xmm0
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/* Test the sign bit */
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test rax, rdx
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/* If it is set, go to the failure path */
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jnz x_is_negative
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/* x is positive, now check if it is NaN by checking if the unsigned
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integer value is larger than the highest valid positive value. */
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mov rcx, HEX(7FF0000000000000)
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cmp rax, rcx
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ja short x_is_nan
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/* All is well, calculate the sqrt */
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sqrtsd xmm0, xmm0
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ret
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x_is_negative:
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/* Load failure return value (-1.#IND00) into rcx */
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mov rcx, HEX(0FFF8000000000000)
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/* Check if the parameter was -0.0 */
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cmp rax, rdx
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/* If it was not, load the failure value, otherwise keep -0.0 */
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cmovne rax, rcx
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/* Move the value back into the return register */
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movd xmm0, rax
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ret
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x_is_nan:
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/* Create a 1.#QNAN0 by setting this bit */
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mov rcx, HEX(8000000000000)
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or rax, rcx
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/* Move the value back into the return register */
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movd xmm0, rax
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ret
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END
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