From 262b7428cfad88de9d328773cc4bae6151b8a030 Mon Sep 17 00:00:00 2001
From: scurest <scurest@users.noreply.github.com>
Date: Tue, 24 Oct 2017 14:18:50 -0500
Subject: [PATCH] More corrections to float printing

Testing suggests all f32s are now printed accurately.
---
 std/fmt/errol/index.zig | 10 +++-------
 std/fmt/index.zig       | 25 +++++++++++++------------
 2 files changed, 16 insertions(+), 19 deletions(-)

diff --git a/std/fmt/errol/index.zig b/std/fmt/errol/index.zig
index 8cf13bca2..0a1ea7dee 100644
--- a/std/fmt/errol/index.zig
+++ b/std/fmt/errol/index.zig
@@ -32,7 +32,7 @@ pub fn errol3(value: f64, buffer: []u8) -> FloatDecimal {
 fn errol3u(val: f64, buffer: []u8) -> FloatDecimal {
     // check if in integer or fixed range
 
-    if (val >= 9.007199254740992e15 and val < 3.40282366920938e+38) {
+    if (val > 9.007199254740992e15 and val < 3.40282366920938e+38) {
         return errolInt(val, buffer);
     } else if (val >= 16.0 and val < 9.007199254740992e15) {
         return errolFixed(val, buffer);
@@ -235,7 +235,7 @@ fn hpMul10(hp: &HP) {
 fn errolInt(val: f64, buffer: []u8) -> FloatDecimal {
     const pow19 = u128(1e19);
 
-    assert((val >= 9.007199254740992e15) and val < (3.40282366920938e38));
+    assert((val > 9.007199254740992e15) and val < (3.40282366920938e38));
 
     var mid = u128(val);
     var low: u128 = mid - fpeint((fpnext(val) - val) / 2.0);
@@ -510,10 +510,6 @@ fn u64toa(value_param: u64, buffer: []u8) -> usize {
         buf_index += 1;
         buffer[buf_index] = c_digits_lut[d8];
         buf_index += 1;
-        buffer[buf_index] = c_digits_lut[d8];
-        buf_index += 1;
-        buffer[buf_index] = c_digits_lut[d8];
-        buf_index += 1;
         buffer[buf_index] = c_digits_lut[d8 + 1];
         buf_index += 1;
     } else {
@@ -613,7 +609,7 @@ fn fpeint(from: f64) -> u128 {
     const bits = @bitCast(u64, from);
     assert((bits & ((1 << 52) - 1)) == 0);
 
-    return u64(1) << u6(((bits >> 52) - 1023));
+    return u128(1) << @truncate(u7, (bits >> 52) -% 1023);
 }
 
 
diff --git a/std/fmt/index.zig b/std/fmt/index.zig
index 85688b361..0fece54b4 100644
--- a/std/fmt/index.zig
+++ b/std/fmt/index.zig
@@ -250,20 +250,17 @@ pub fn formatFloat(value: var, context: var, output: fn(@typeOf(context), []cons
     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 (math.signbit(x)) {
         if (!output(context, "-"))
             return false;
         x = -x;
     }
+    if (math.isPositiveInf(x)) {
+        return output(context, "Infinity");
+    }
+    if (x == 0.0) {
+        return output(context, "0.0");
+    }
 
     var buffer: [32]u8 = undefined;
     const float_decimal = errol3(x, buffer[0..]);
@@ -272,8 +269,12 @@ pub fn formatFloat(value: var, context: var, output: fn(@typeOf(context), []cons
     if (!output(context, "."))
         return false;
     if (float_decimal.digits.len > 1) {
-        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)]))
+        const num_digits = if (@typeOf(value) == f32) {
+            math.min(usize(9), float_decimal.digits.len)
+        } else {
+            float_decimal.digits.len
+        };
+        if (!output(context, float_decimal.digits[1 .. num_digits]))
             return false;
     } else {
         if (!output(context, "0"))