lib: Add lib and libm, moving current files from stmhal.

Top-level lib directory is for standard C libraries that we want to
provide our own versions of (for efficiency and stand-alone reasons).
It currently has libm in it for math functions.

Also add atanf and atan2f, which addresses issue #837.

lib/libm/atan2f.c

@@ -0,0 +1,89 @@
+/*****************************************************************************/
+/*****************************************************************************/
+// atan2f from musl-0.9.15
+/*****************************************************************************/
+/*****************************************************************************/
+
+/* origin: FreeBSD /usr/src/lib/msun/src/e_atan2f.c */
+/*
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+#include "libm.h"
+
+static const float
+pi     = 3.1415927410e+00, /* 0x40490fdb */
+pi_lo  = -8.7422776573e-08; /* 0xb3bbbd2e */
+
+float atan2f(float y, float x)
+{
+	float z;
+	uint32_t m,ix,iy;
+
+	if (isnan(x) || isnan(y))
+		return x+y;
+	GET_FLOAT_WORD(ix, x);
+	GET_FLOAT_WORD(iy, y);
+	if (ix == 0x3f800000)  /* x=1.0 */
+		return atanf(y);
+	m = ((iy>>31)&1) | ((ix>>30)&2);  /* 2*sign(x)+sign(y) */
+	ix &= 0x7fffffff;
+	iy &= 0x7fffffff;
+
+	/* when y = 0 */
+	if (iy == 0) {
+		switch (m) {
+		case 0:
+		case 1: return y;   /* atan(+-0,+anything)=+-0 */
+		case 2: return  pi; /* atan(+0,-anything) = pi */
+		case 3: return -pi; /* atan(-0,-anything) =-pi */
+		}
+	}
+	/* when x = 0 */
+	if (ix == 0)
+		return m&1 ? -pi/2 : pi/2;
+	/* when x is INF */
+	if (ix == 0x7f800000) {
+		if (iy == 0x7f800000) {
+			switch (m) {
+			case 0: return  pi/4; /* atan(+INF,+INF) */
+			case 1: return -pi/4; /* atan(-INF,+INF) */
+			case 2: return 3*pi/4;  /*atan(+INF,-INF)*/
+			case 3: return -3*pi/4; /*atan(-INF,-INF)*/
+			}
+		} else {
+			switch (m) {
+			case 0: return  0.0f;    /* atan(+...,+INF) */
+			case 1: return -0.0f;    /* atan(-...,+INF) */
+			case 2: return  pi; /* atan(+...,-INF) */
+			case 3: return -pi; /* atan(-...,-INF) */
+			}
+		}
+	}
+	/* |y/x| > 0x1p26 */
+	if (ix+(26<<23) < iy || iy == 0x7f800000)
+		return m&1 ? -pi/2 : pi/2;
+
+	/* z = atan(|y/x|) with correct underflow */
+	if ((m&2) && iy+(26<<23) < ix)  /*|y/x| < 0x1p-26, x < 0 */
+		z = 0.0;
+	else
+		z = atanf(fabsf(y/x));
+	switch (m) {
+	case 0: return z;              /* atan(+,+) */
+	case 1: return -z;             /* atan(-,+) */
+	case 2: return pi - (z-pi_lo); /* atan(+,-) */
+	default: /* case 3 */
+		return (z-pi_lo) - pi; /* atan(-,-) */
+	}
+}

lib/libm/atanf.c

@@ -0,0 +1,100 @@
+/*****************************************************************************/
+/*****************************************************************************/
+// atanf from musl-0.9.15
+/*****************************************************************************/
+/*****************************************************************************/
+
+/* origin: FreeBSD /usr/src/lib/msun/src/s_atanf.c */
+/*
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+
+#include "libm.h"
+
+static const float atanhi[] = {
+  4.6364760399e-01, /* atan(0.5)hi 0x3eed6338 */
+  7.8539812565e-01, /* atan(1.0)hi 0x3f490fda */
+  9.8279368877e-01, /* atan(1.5)hi 0x3f7b985e */
+  1.5707962513e+00, /* atan(inf)hi 0x3fc90fda */
+};
+
+static const float atanlo[] = {
+  5.0121582440e-09, /* atan(0.5)lo 0x31ac3769 */
+  3.7748947079e-08, /* atan(1.0)lo 0x33222168 */
+  3.4473217170e-08, /* atan(1.5)lo 0x33140fb4 */
+  7.5497894159e-08, /* atan(inf)lo 0x33a22168 */
+};
+
+static const float aT[] = {
+  3.3333328366e-01,
+ -1.9999158382e-01,
+  1.4253635705e-01,
+ -1.0648017377e-01,
+  6.1687607318e-02,
+};
+
+float atanf(float x)
+{
+	float_t w,s1,s2,z;
+	uint32_t ix,sign;
+	int id;
+
+	GET_FLOAT_WORD(ix, x);
+	sign = ix>>31;
+	ix &= 0x7fffffff;
+	if (ix >= 0x4c800000) {  /* if |x| >= 2**26 */
+		if (isnan(x))
+			return x;
+		z = atanhi[3] + 0x1p-120f;
+		return sign ? -z : z;
+	}
+	if (ix < 0x3ee00000) {   /* |x| < 0.4375 */
+		if (ix < 0x39800000) {  /* |x| < 2**-12 */
+			if (ix < 0x00800000)
+				/* raise underflow for subnormal x */
+				FORCE_EVAL(x*x);
+			return x;
+		}
+		id = -1;
+	} else {
+		x = fabsf(x);
+		if (ix < 0x3f980000) {  /* |x| < 1.1875 */
+			if (ix < 0x3f300000) {  /*  7/16 <= |x| < 11/16 */
+				id = 0;
+				x = (2.0f*x - 1.0f)/(2.0f + x);
+			} else {                /* 11/16 <= |x| < 19/16 */
+				id = 1;
+				x = (x - 1.0f)/(x + 1.0f);
+			}
+		} else {
+			if (ix < 0x401c0000) {  /* |x| < 2.4375 */
+				id = 2;
+				x = (x - 1.5f)/(1.0f + 1.5f*x);
+			} else {                /* 2.4375 <= |x| < 2**26 */
+				id = 3;
+				x = -1.0f/x;
+			}
+		}
+	}
+	/* end of argument reduction */
+	z = x*x;
+	w = z*z;
+	/* break sum from i=0 to 10 aT[i]z**(i+1) into odd and even poly */
+	s1 = z*(aT[0]+w*(aT[2]+w*aT[4]));
+	s2 = w*(aT[1]+w*aT[3]);
+	if (id < 0)
+		return x - x*(s1+s2);
+	z = atanhi[id] - ((x*(s1+s2) - atanlo[id]) - x);
+	return sign ? -z : z;
+}

lib/libm/libm.h

@@ -0,0 +1,52 @@
+/*****************************************************************************/
+/*****************************************************************************/
+// portions extracted from musl-0.9.15 libm.h
+/*****************************************************************************/
+/*****************************************************************************/
+
+/* origin: FreeBSD /usr/src/lib/msun/src/math_private.h */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+#include <stdint.h>
+#include <math.h>
+
+#define FORCE_EVAL(x) do {                        \
+	if (sizeof(x) == sizeof(float)) {         \
+		volatile float __x;               \
+		__x = (x);                        \
+                (void)__x;                        \
+	} else if (sizeof(x) == sizeof(double)) { \
+		volatile double __x;              \
+		__x = (x);                        \
+                (void)__x;                        \
+	} else {                                  \
+		volatile long double __x;         \
+		__x = (x);                        \
+                (void)__x;                        \
+	}                                         \
+} while(0)
+
+/* Get a 32 bit int from a float.  */
+#define GET_FLOAT_WORD(w,d)                       \
+do {                                              \
+  union {float f; uint32_t i;} __u;               \
+  __u.f = (d);                                    \
+  (w) = __u.i;                                    \
+} while (0)
+
+/* Set a float from a 32 bit int.  */
+#define SET_FLOAT_WORD(d,w)                       \
+do {                                              \
+      union {float f; uint32_t i;} __u;           \
+      __u.i = (w);                                \
+      (d) = __u.f;                                \
+} while (0)

lib/libm/math.c

@@ -24,8 +24,7 @@
  * THE SOFTWARE.
  */
 
-#include <stdint.h>
+#include "libm.h"
-#include <math.h>
 
 typedef float float_t;
 typedef union {
@@ -117,11 +116,8 @@ float tanhf(float x) { return sinhf(x) / coshf(x); }
 float acoshf(float x) { return 0.0; }
 float asinhf(float x) { return 0.0; }
 float atanhf(float x) { return 0.0; }
-float tanf(float x) { return 0.0; }
 float acosf(float x) { return 0.0; }
 float asinf(float x) { return 0.0; }
-float atanf(float x) { return 0.0; }
-float atan2f(float x, float y) { return 0.0; }
 float fmodf(float x, float y) { return 0.0; }
 float tgammaf(float x) { return 0.0; }
 float lgammaf(float x) { return 0.0; }
@@ -131,56 +127,6 @@ float modff(float x, float *y) { return 0.0; }
 float frexpf(float x, int *exp) { return 0.0; }
 float ldexpf(float x, int exp) { return 0.0; }
 
-/*****************************************************************************/
-/*****************************************************************************/
-// from musl-0.9.15 libm.h
-/*****************************************************************************/
-/*****************************************************************************/
-
-/* origin: FreeBSD /usr/src/lib/msun/src/math_private.h */
-/*
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunPro, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice
- * is preserved.
- * ====================================================
- */
-
-#define FORCE_EVAL(x) do {                        \
-	if (sizeof(x) == sizeof(float)) {         \
-		volatile float __x;               \
-		__x = (x);                        \
-                (void)__x;                        \
-	} else if (sizeof(x) == sizeof(double)) { \
-		volatile double __x;              \
-		__x = (x);                        \
-                (void)__x;                        \
-	} else {                                  \
-		volatile long double __x;         \
-		__x = (x);                        \
-                (void)__x;                        \
-	}                                         \
-} while(0)
-
-/* Get a 32 bit int from a float.  */
-#define GET_FLOAT_WORD(w,d)                       \
-do {                                              \
-  union {float f; uint32_t i;} __u;               \
-  __u.f = (d);                                    \
-  (w) = __u.i;                                    \
-} while (0)
-
-/* Set a float from a 32 bit int.  */
-#define SET_FLOAT_WORD(d,w)                       \
-do {                                              \
-      union {float f; uint32_t i;} __u;           \
-      __u.i = (w);                                \
-      (d) = __u.f;                                \
-} while (0)
-
 /*****************************************************************************/
 /*****************************************************************************/
 // __fpclassifyf from musl-0.9.15

stmhal/Makefile

@@ -60,6 +60,13 @@ endif
 # uncomment this if you want libgcc
 #LIBS += $(shell $(CC) -print-libgcc-file-name)
 
+SRC_LIB = $(addprefix lib/,\
+	libm/math.c \
+	libm/mathsincos.c \
+	libm/atanf.c \
+	libm/atan2f.c \
+	)
+
 SRC_C = \
 	main.c \
 	string0.c \
@@ -84,8 +91,6 @@ SRC_C = \
 	uart.c \
 	usb.c \
 	printf.c \
-	math.c \
-	mathsincos.c \
 	gccollect.c \
 	pybstdio.c \
 	readline.c \
@@ -193,6 +198,7 @@ SRC_CC3K = $(addprefix $(CC3K_DIR)/,\
 
 OBJ =
 OBJ += $(PY_O)
+OBJ += $(addprefix $(BUILD)/, $(SRC_LIB:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_S:.s=.o))
 OBJ += $(addprefix $(BUILD)/, $(SRC_HAL:.c=.o))