;;;; mathh.scm
;;;; Provides access to ISO C math functions in <math.h>
;;;; that are not defined by Chicken
;;;; Public domain

;;; Scheme-level declarations
(declare (bound-to-procedure cosh sinh tanh log10 fmod modf ldexp frexp))

;;; Include proper C header
(foreign-declare "#include <math.h>")

;;; Hyperbolic functions
(define cosh (foreign-lambda double cosh double))
(define sinh (foreign-lambda double sinh double))
(define tanh (foreign-lambda double tanh double))

;;; Base-10 logarithm
(define log10 (foreign-lambda double log10 double))

;;; Flonum remainder
(define fmod (foreign-lambda double fmod double double))

;;; Return integer, fraction (as multiple values) of a flonum
(define modf (foreign-primitive ((double x))
	"double ipart;
	 double result;
	 C_word* values;
	 C_word value1;
	 C_word value2;

	 result = modf(x, &ipart);
	 values = C_alloc(2*C_SIZEOF_FLONUM);
	 value1 = C_flonum(&values, ipart);
	 value2 = C_flonum(&values, result);
	 C_values(4, C_SCHEME_UNDEFINED, C_k, value1, value2);
	"))

;;; Efficiently compute (* x (expt 2 y))
(define ldexp (foreign-lambda double ldexp double double))

;;; Return mantissa, exponent (as multiple values) of a flonum
(define frexp (foreign-primitive ((double x))
	"int exp;
	 double result;
	 C_word* values;
	 C_word value1;
	 C_word value2;

	 result = frexp(x, &exp);
	 values = C_alloc(C_SIZEOF_FLONUM);
	 value1 = C_flonum(&values, result);
	 value2 = C_fix(exp);
	 C_values(4, C_SCHEME_UNDEFINED, C_k, value1, value2);
	"))