1*17329Ssam/* ldexp.s 4.2 84/11/01 */ 213416Sroot 313416Sroot/* 413416Sroot * double ldexp (value, exp) 513416Sroot * double value; 613416Sroot * int exp; 713416Sroot * 813416Sroot * Ldexp returns value*2**exp, if that result is in range. 913416Sroot * If underflow occurs, it returns zero. If overflow occurs, 1013416Sroot * it returns a value of appropriate sign and largest 1113416Sroot * possible magnitude. In case of either overflow or underflow, 1213416Sroot * errno is set to ERANGE. Note that errno is not modified if 1313416Sroot * no error occurs. 1413416Sroot */ 1513416Sroot 1613416Sroot#include "DEFS.h" 1713416Sroot#include <errno.h> 1813416Sroot 1913416Sroot .globl _errno 2013416Sroot 21*17329SsamENTRY(ldexp, 0) 2213416Sroot movd 4(ap),r0 /* fetch "value" */ 2313416Sroot extzv $7,$8,r0,r2 /* r2 := biased exponent */ 2413416Sroot jeql 1f /* if zero, done */ 2513416Sroot 2613416Sroot addl2 12(ap),r2 /* r2 := new biased exponent */ 2713416Sroot jleq 2f /* if <= 0, underflow */ 2813416Sroot cmpl r2,$256 /* otherwise check if too big */ 2913416Sroot jgeq 3f /* jump if overflow */ 3013416Sroot insv r2,$7,$8,r0 /* put exponent back in result */ 3113416Sroot1: 3213416Sroot ret 3313416Sroot2: 3413416Sroot clrd r0 3513416Sroot jbr 1f 3613416Sroot3: 3713416Sroot movd huge,r0 /* largest possible floating magnitude */ 3813416Sroot jbc $15,4(ap),1f /* jump if argument was positive */ 3913416Sroot mnegd r0,r0 /* if arg < 0, make result negative */ 4013416Sroot1: 4113416Sroot movl $ERANGE,_errno 4213416Sroot ret 4313416Sroot 4413416Sroot .data 4513416Sroothuge: .word 0x7fff /* the largest number that can */ 4613416Sroot .word 0xffff /* be represented in a long floating */ 4713416Sroot .word 0xffff /* number. This is given in hex in order */ 4813416Sroot .word 0xffff /* to avoid floating conversions */ 49