1*2f2c0062Sguenther /* $OpenBSD: e_sqrt.c,v 1.7 2016/09/12 19:47:02 guenther Exp $ */ 2f0a70dfeSmartynas 3f0a70dfeSmartynas /* 4f0a70dfeSmartynas * Written by Martynas Venckus. Public domain 5f0a70dfeSmartynas */ 6f0a70dfeSmartynas 7f0a70dfeSmartynas #include <sys/types.h> 8f0a70dfeSmartynas #include <math.h> 9f0a70dfeSmartynas 10f0a70dfeSmartynas #define FPSCR_PR (1 << 19) 11f0a70dfeSmartynas #define FPSCR_SZ (1 << 20) 12f0a70dfeSmartynas 13f0a70dfeSmartynas double sqrt(double d)14f0a70dfeSmartynassqrt(double d) 15f0a70dfeSmartynas { 16f0a70dfeSmartynas register_t fpscr, nfpscr; 17f0a70dfeSmartynas 18b5aa3b33Sguenther __asm__ volatile ("sts fpscr, %0" : "=r" (fpscr)); 19f0a70dfeSmartynas 20f0a70dfeSmartynas /* Set floating-point mode to double-precision. */ 21f0a70dfeSmartynas nfpscr = fpscr | FPSCR_PR; 22f0a70dfeSmartynas 23f0a70dfeSmartynas /* Do not set SZ and PR to 1 simultaneously. */ 24f0a70dfeSmartynas nfpscr &= ~FPSCR_SZ; 25f0a70dfeSmartynas 26b5aa3b33Sguenther __asm__ volatile ("lds %0, fpscr" : : "r" (nfpscr)); 27b5aa3b33Sguenther __asm__ volatile ("fsqrt %0" : "+f" (d)); 28f0a70dfeSmartynas 29f0a70dfeSmartynas /* Restore fp status/control register. */ 30b5aa3b33Sguenther __asm__ volatile ("lds %0, fpscr" : : "r" (fpscr)); 31f0a70dfeSmartynas 32f0a70dfeSmartynas return (d); 33f0a70dfeSmartynas } 34*2f2c0062Sguenther DEF_STD(sqrt); 35*2f2c0062Sguenther LDBL_CLONE(sqrt); 36