floatscan-experiment.c: reformat the original code

c-programming/experiments/floatscan-experiment.c

@@ -2,9 +2,35 @@
  * This was an experiment to learn about how libc turn floating point strings
  * into actual values.
  *
- * The original code is from musl libc: version 1.2.4, src/internal/floatscan.c
+ * The original code is licensed to and was taken from musl libc, originally
+ * stored at src/internal/floatscan.c
  *
- * The added code:
+ * musl libc is licensed under MIT license:
+ *     musl as a whole is licensed under the following standard MIT license:
+ *
+ *     ----------------------------------------------------------------------
+ *     Copyright © 2005-2020 Rich Felker, et al.
+ *
+ *     Permission is hereby granted, free of charge, to any person obtaining
+ *     a copy of this software and associated documentation files (the
+ *     "Software"), to deal in the Software without restriction, including
+ *     without limitation the rights to use, copy, modify, merge, publish,
+ *     distribute, sublicense, and/or sell copies of the Software, and to
+ *     permit persons to whom the Software is furnished to do so, subject to
+ *     the following conditions:
+ *
+ *     The above copyright notice and this permission notice shall be
+ *     included in all copies or substantial portions of the Software.
+ *
+ *     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ *     EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ *     MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ *     IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ *     CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ *     TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ *     SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * The license information of the added code and this modification:
  *     Author: Intel A80486DX2-66
  *     License: Creative Commons Zero 1.0 Universal
  */
@@ -68,7 +94,7 @@ static long long scanexp(FILE *f, int pok)
 	int x;
 	long long y;
 	int neg = 0;
-	
+
 	c = shgetc(f);
 	if (c=='+' || c=='-') {
 		neg = (c=='-');
@@ -214,7 +240,7 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 			x[k] = x[k]/p10 + carry;
 			carry = 1000000000/p10 * tmp;
 			if (k==a && !x[k]) {
-				a = (a+1 & MASK);
+				a = ((a+1) & MASK);
 				rp -= 9;
 			}
 		}
@@ -226,7 +252,7 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 	while (rp < 9*LD_B1B_DIG || (rp == 9*LD_B1B_DIG && x[a]<th[0])) {
 		uint32_t carry = 0;
 		e2 -= 29;
-		for (k=(z-1 & MASK); ; k=(k-1 & MASK)) {
+		for (k=(z-1) & MASK; ; k=(k-1) & MASK) {
 			uint64_t tmp = ((uint64_t)x[k] << 29) + carry;
 			if (tmp > 1000000000) {
 				carry = tmp / 1000000000;
@@ -235,15 +261,15 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 				carry = 0;
 				x[k] = tmp;
 			}
-			if (k==(z-1 & MASK) && k!=a && !x[k]) z = k;
+			if (k==((z-1) & MASK) && k!=a && !x[k]) z = k;
 			if (k==a) break;
 		}
 		if (carry) {
 			rp += 9;
-			a = (a-1 & MASK);
+			a = ((a-1) & MASK);
 			if (a == z) {
-				z = (z-1 & MASK);
+				z = (z-1) & MASK;
-				x[z-1 & MASK] |= x[z];
+				x[(z-1) & MASK] |= x[z];
 			}
 			x[a] = carry;
 		}
@@ -254,39 +280,39 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 		uint32_t carry = 0;
 		int sh = 1;
 		for (i=0; i<LD_B1B_DIG; i++) {
-			k = (a+i & MASK);
+			k = ((a+i) & MASK);
 			if (k == z || x[k] < th[i]) {
 				i=LD_B1B_DIG;
 				break;
 			}
-			if (x[a+i & MASK] > th[i]) break;
+			if (x[(a+i) & MASK] > th[i]) break;
 		}
 		if (i==LD_B1B_DIG && rp==9*LD_B1B_DIG) break;
 		/* FIXME: find a way to compute optimal sh */
 		if (rp > 9+9*LD_B1B_DIG) sh = 9;
 		e2 += sh;
-		for (k=a; k!=z; k=(k+1 & MASK)) {
+		for (k=a; k!=z; k=(k+1) & MASK) {
-			uint32_t tmp = x[k] & (1<<sh)-1;
+			uint32_t tmp = x[k] & ((1<<sh)-1);
 			x[k] = (x[k]>>sh) + carry;
 			carry = (1000000000>>sh) * tmp;
 			if (k==a && !x[k]) {
-				a = (a+1 & MASK);
+				a = (a+1) & MASK;
 				i--;
 				rp -= 9;
 			}
 		}
 		if (carry) {
-			if ((z+1 & MASK) != a) {
+			if (((z+1) & MASK) != a) {
 				x[z] = carry;
-				z = (z+1 & MASK);
+				z = (z+1) & MASK;
-			} else x[z-1 & MASK] |= 1;
+			} else x[(z-1) & MASK] |= 1;
 		}
 	}
 
 	/* Assemble desired bits into floating point variable */
 	for (y=i=0; i<LD_B1B_DIG; i++) {
-		if ((a+i & MASK)==z) x[(z=(z+1 & MASK))-1] = 0;
+		if (((a+i) & MASK)==z) x[(z=((z+1) & MASK))-1] = 0;
-		y = 1000000000.0L * y + x[a+i & MASK];
+		y = 1000000000.0L * y + x[(a+i) & MASK];
 	}
 
 	y *= sign;
@@ -307,14 +333,14 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 	}
 
 	/* Process tail of decimal input so it can affect rounding */
-	if ((a+i & MASK) != z) {
+	if (((a+i) & MASK) != z) {
-		uint32_t t = x[a+i & MASK];
+		uint32_t t = x[(a+i) & MASK];
-		if (t < 500000000 && (t || (a+i+1 & MASK) != z))
+		if (t < 500000000 && (t || ((a+i+1) & MASK) != z))
 			frac += 0.25*sign;
 		else if (t > 500000000)
 			frac += 0.75*sign;
 		else if (t == 500000000) {
-			if ((a+i+1 & MASK) == z)
+			if (((a+i+1) & MASK) == z)
 				frac += 0.5*sign;
 			else
 				frac += 0.75*sign;
@@ -326,7 +352,7 @@ static long double decfloat(FILE *f, int c, int bits, int emin, int sign, int po
 	y += frac;
 	y -= bias;
 
-	if ((e2+LDBL_MANT_DIG & INT_MAX) > emax-5) {
+	if (((e2+LDBL_MANT_DIG) & INT_MAX) > emax-5) {
 		if (fabsl(y) >= 2/LDBL_EPSILON) {
 			if (denormal && bits==LDBL_MANT_DIG+e2-emin)
 				denormal = 0;