6b89b6f945
* arch/arm/src/sama5/sam_flexcom_spi.h, arch/risc-v/src/mpfs/mpfs_ihc_sbi.c, drivers/usbdev/adb.c, libs/libc/math/lib_scalbn.c, libs/libc/math/lib_scalbnf.c, net/ipfrag/Make.defs, net/ipfrag/ipfrag.c, net/ipfrag/ipfrag.h, net/ipfrag/ipv4_frag.c, net/ipfrag/ipv6_frag.c: Remove executable permission.
89 lines
2.2 KiB
C
89 lines
2.2 KiB
C
/****************************************************************************
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* libs/libc/math/lib_scalbn.c
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* get a double number of x*2^n
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*
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* This file is copy from musl libc
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* musl is an implementation of the C standard library built on top of the
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* Linux system call API, including interfaces defined in the base language
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* standard, POSIX, and widely agreed-upon extensions.
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* musl is lightweight, fast, simple, free, and strives to be correct in
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* the sense of standards-conformance and safety.
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*
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <math.h>
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#include <stdint.h>
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/****************************************************************************
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* Pre-processor definitions
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****************************************************************************/
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#ifdef CONFIG_HAVE_DOUBLE
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#define DOUBLE_MIN (0x1p-1022)
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: scalbn
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*
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* Description:
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* get a double number of x*2^n
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*
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****************************************************************************/
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double scalbn(double x, int n)
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{
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union
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{
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double f;
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uint64_t i;
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}u;
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double_t y = x;
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if (n > 1023)
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{
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y *= 0x1p1023;
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n -= 1023;
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if (n > 1023)
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{
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y *= 0x1p1023;
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n -= 1023;
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if (n > 1023)
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{
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n = 1023;
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}
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}
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}
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else if (n < -1022)
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{
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/* make sure final n < -53 to avoid double
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* rounding in the subnormal range
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*/
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y *= DOUBLE_MIN * 0x1p53;
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n += 1022 - 53;
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if (n < -1022)
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{
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y *= DOUBLE_MIN * 0x1p53;
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n += 1022 - 53;
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if (n < -1022)
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{
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n = -1022;
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}
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}
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}
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u.i = (uint64_t)(0x3ff + n) << 52;
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x = y * u.f;
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return x;
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}
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#endif /* CONFIG_HAVE_DOUBLE */
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