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Print better floats

master
scurest 2017-10-23 15:40:49 -05:00
parent c1642355f0
commit 03a0dfbeca
2 changed files with 34 additions and 18 deletions
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12
std/fmt/errol/index.zig
View File

@ -38,7 +38,7 @@ fn errol3u(val: f64, buffer: []u8) -> FloatDecimal {
return errolFixed(val, buffer);
}
// normalize the midpoint
const e = math.frexp(val).exponent;
@ -138,7 +138,7 @@ fn tableLowerBound(k: u64) -> usize {
while (j < enum3.len) {
if (enum3[j] < k) {
j = 2 * k + 2;
j = 2 * j + 2;
} else {
i = j;
j = 2 * j + 1;
@ -217,7 +217,7 @@ fn hpMul10(hp: &HP) {
hp.val *= 10.0;
hp.off *= 10.0;
var off = hp.val;
off -= val * 8.0;
off -= val * 2.0;
@ -241,7 +241,7 @@ fn errolInt(val: f64, buffer: []u8) -> FloatDecimal {
var low: u128 = mid - fpeint((fpnext(val) - val) / 2.0);
var high: u128 = mid + fpeint((val - fpprev(val)) / 2.0);
if (@bitCast(u64, val) & 0x1 != 0) {
if (@bitCast(u64, val) & 0x1 != 0) {
high -= 1;
} else {
low -= 1;
@ -347,11 +347,11 @@ fn errolFixed(val: f64, buffer: []u8) -> FloatDecimal {
}
fn fpnext(val: f64) -> f64 {
return @bitCast(f64, @bitCast(u64, val) + 1);
return @bitCast(f64, @bitCast(u64, val) +% 1);
}
fn fpprev(val: f64) -> f64 {
return @bitCast(f64, @bitCast(u64, val) - 1);
return @bitCast(f64, @bitCast(u64, val) -% 1);
}
pub const c_digits_lut = []u8 {

40
std/fmt/index.zig
View File

@ -244,30 +244,46 @@ pub fn formatBuf(buf: []const u8, width: usize,
}
pub fn formatFloat(value: var, context: var, output: fn(@typeOf(context), []const u8)->bool) -> bool {
var buffer: [20]u8 = undefined;
const float_decimal = errol3(f64(value), buffer[0..]);
if (float_decimal.exp != 0) {
if (!output(context, float_decimal.digits[0..1]))
return false;
} else {
if (!output(context, "0"))
return false;
var x = f64(value);
// Errol doesn't handle these special cases.
if (math.isNan(x)) {
return output(context, "NaN");
}
if (math.isPositiveInf(x)) {
return output(context, "Infinity");
}
if (math.isNegativeInf(x)) {
return output(context, "-Infinity");
}
if (x == 0.0) {
return output(context, "0.0");
}
if (x < 0.0) {
if (!output(context, "-"))
return false;
x = -x;
}
var buffer: [32]u8 = undefined;
const float_decimal = errol3(x, buffer[0..]);
if (!output(context, float_decimal.digits[0..1]))
return false;
if (!output(context, "."))
return false;
if (float_decimal.digits.len > 1) {
const start = if (float_decimal.exp == 0) usize(0) else usize(1);
if (!output(context, float_decimal.digits[start .. math.min(usize(7), float_decimal.digits.len)]))
const num_digits = if (@typeOf(value) == f32) { usize(8) } else { usize(17) };
if (!output(context, float_decimal.digits[1 .. math.min(num_digits, float_decimal.digits.len)]))
return false;
} else {
if (!output(context, "0"))
return false;
}
if (float_decimal.exp != 1 and float_decimal.exp != 0) {
if (float_decimal.exp != 1) {
if (!output(context, "e"))
return false;
if (!formatInt(float_decimal.exp, 10, false, 0, context, output))
if (!formatInt(float_decimal.exp - 1, 10, false, 0, context, output))
return false;
}
return true;