From c5015be7831e612db3889443c425a4d9a0a90aae Mon Sep 17 00:00:00 2001
From: Kogia-sima <orcinus4627@gmail.com>
Date: Wed, 10 Jun 2020 18:33:31 +0900
Subject: [PATCH] Add new module (sailfish::runtime::integer)

---
 sailfish/src/runtime/integer.rs | 360 ++++++++++++++++++++++++++++++++
 sailfish/src/runtime/mod.rs     |   1 +
 2 files changed, 361 insertions(+)
 create mode 100644 sailfish/src/runtime/integer.rs

diff --git a/sailfish/src/runtime/integer.rs b/sailfish/src/runtime/integer.rs
new file mode 100644
index 0000000..0e91378
--- /dev/null
+++ b/sailfish/src/runtime/integer.rs
@@ -0,0 +1,360 @@
+use std::ptr;
+
+const DEC_DIGITS_LUT: &'static [u8] = b"\
+      0001020304050607080910111213141516171819\
+      2021222324252627282930313233343536373839\
+      4041424344454647484950515253545556575859\
+      6061626364656667686970717273747576777879\
+      8081828384858687888990919293949596979899";
+
+macro_rules! lookup {
+    ($idx:expr) => {
+        DEC_DIGITS_LUT.as_ptr().add(($idx as usize) << 1)
+    };
+}
+
+/// write integer smaller than 10000
+#[inline]
+unsafe fn write_small(n: u16, buf: *mut u8) -> usize {
+    debug_assert!(n < 10000);
+
+    if n < 100 {
+        if n < 10 {
+            *buf = n as u8 + 0x30;
+            1
+        } else {
+            ptr::copy_nonoverlapping(lookup!(n), buf, 2);
+            2
+        }
+    } else {
+        if n < 1000 {
+            let d1 = (n / 100) as u8;
+            let d2 = n % 100;
+            *buf = d1 + 0x30;
+            ptr::copy_nonoverlapping(lookup!(d2), buf.add(1), 2);
+            3
+        } else {
+            let d1 = n / 100;
+            let d2 = n % 100;
+            ptr::copy_nonoverlapping(lookup!(d1), buf, 2);
+            ptr::copy_nonoverlapping(lookup!(d2), buf.add(2), 2);
+            4
+        }
+    }
+}
+
+/// write integer smaller with 0 padding
+#[inline]
+unsafe fn write_small_pad(n: u16, buf: *mut u8) {
+    debug_assert!(n < 10000);
+
+    let d1 = n / 100;
+    let d2 = n % 100;
+
+    ptr::copy_nonoverlapping(lookup!(d1), buf, 2);
+    ptr::copy_nonoverlapping(lookup!(d2), buf.add(2), 2);
+}
+
+#[inline]
+unsafe fn write_u8(n: u8, buf: *mut u8) -> usize {
+    if n < 10 {
+        *buf = n + 0x30;
+        1
+    } else if n < 100 {
+        ptr::copy_nonoverlapping(lookup!(n), buf, 2);
+        2
+    } else {
+        let d1 = n / 100;
+        let d2 = n % 100;
+        *buf = d1 + 0x30;
+        ptr::copy_nonoverlapping(lookup!(d2), buf.add(1), 2);
+        3
+    }
+}
+
+#[inline]
+unsafe fn write_u16(n: u16, buf: *mut u8) -> usize {
+    if n < 100 {
+        if n < 10 {
+            *buf = n as u8 + 0x30;
+            1
+        } else {
+            ptr::copy_nonoverlapping(lookup!(n), buf, 2);
+            2
+        }
+    } else if n < 10000 {
+        if n < 1000 {
+            let d1 = (n / 100) as u8;
+            let d2 = n % 100;
+            *buf = d1 + 0x30;
+            ptr::copy_nonoverlapping(lookup!(d2), buf.add(1), 2);
+            3
+        } else {
+            let d1 = n / 100;
+            let d2 = n % 100;
+            ptr::copy_nonoverlapping(lookup!(d1), buf, 2);
+            ptr::copy_nonoverlapping(lookup!(d2), buf.add(2), 2);
+            4
+        }
+    } else {
+        let b = (n / 10000) as u8; // 1 to 6
+        let c = n % 10000;
+
+        *buf = b + 0x30;
+        write_small_pad(c, buf.add(1));
+        5
+    }
+}
+
+#[inline]
+unsafe fn write_u32(mut n: u32, buf: *mut u8) -> usize {
+    if n < 10000 {
+        write_small(n as u16, buf)
+    } else if n < 100000000 {
+        let b = n / 10000;
+        let c = n % 10000;
+
+        let l = write_small(b as u16, buf);
+        write_small_pad(c as u16, buf.add(l));
+        l + 4
+    } else {
+        let a = n / 100000000; // 1 to 42
+        n %= 100000000;
+
+        let l = if a >= 10 {
+            ptr::copy_nonoverlapping(lookup!(a), buf, 2);
+            2
+        } else {
+            *buf = a as u8 + 0x30;
+            1
+        };
+
+        let b = n / 10000;
+        let c = n % 10000;
+
+        write_small_pad(b as u16, buf.add(l));
+        write_small_pad(c as u16, buf.add(l + 4));
+        l + 8
+    }
+}
+
+#[inline]
+unsafe fn write_u64(mut n: u64, buf: *mut u8) -> usize {
+    if n < 10000 {
+        write_small(n as u16, buf)
+    } else if n < 100000000 {
+        let n = n as u32;
+        let b = n / 10000;
+        let c = n % 10000;
+
+        let l = write_small(b as u16, buf);
+        write_small_pad(c as u16, buf.add(l));
+        l + 4
+    } else if n < 10000000000000000 {
+        let v0 = n / 100000000;
+        let v1 = (n % 100000000) as u32;
+
+        let l = if v0 < 10000 {
+            write_small(v0 as u16, buf)
+        } else {
+            let b0 = v0 / 10000;
+            let c0 = v0 % 10000;
+            let l = write_small(b0 as u16, buf);
+            write_small_pad(c0 as u16, buf.add(l));
+            l + 4
+        };
+
+        let b1 = v1 / 10000;
+        let c1 = v1 % 10000;
+
+        write_small_pad(b1 as u16, buf.add(l));
+        write_small_pad(c1 as u16, buf.add(l + 4));
+
+        l + 8
+    } else {
+        let a = n / 10000000000000000; // 1 to 1844
+        n %= 10000000000000000;
+
+        let v0 = (n / 100000000) as u32;
+        let v1 = (n % 100000000) as u32;
+
+        let b0 = v0 / 10000;
+        let c0 = v0 % 10000;
+
+        let b1 = v1 / 10000;
+        let c1 = v1 % 10000;
+
+        let l = write_small(a as u16, buf);
+        write_small_pad(b0 as u16, buf.add(l));
+        write_small_pad(c0 as u16, buf.add(l + 4));
+        write_small_pad(b1 as u16, buf.add(l + 8));
+        write_small_pad(c1 as u16, buf.add(l + 12));
+        l + 16
+    }
+}
+
+pub trait Integer {
+    const MAX_LEN: usize;
+    unsafe fn write_to(self, buf: *mut u8) -> usize;
+}
+
+macro_rules! impl_integer {
+    ($unsigned:ty, $signed:ty, $conv:ty, $func:ident, $max_len:expr) => {
+        impl Integer for $unsigned {
+            const MAX_LEN: usize = $max_len;
+
+            #[inline]
+            unsafe fn write_to(self, buf: *mut u8) -> usize {
+                $func(self as $conv, buf)
+            }
+        }
+
+        impl Integer for $signed {
+            const MAX_LEN: usize = $max_len + 1;
+
+            #[inline]
+            unsafe fn write_to(self, mut buf: *mut u8) -> usize {
+                if self >= 0 {
+                    $func(self as $conv, buf)
+                } else {
+                    *buf = b'-';
+                    buf = buf.add(1);
+                    let n = (!(self as $conv)).wrapping_add(1);
+                    $func(n, buf) + 1
+                }
+            }
+        }
+    };
+}
+
+impl_integer!(u8, i8, u8, write_u8, 3);
+impl_integer!(u16, i16, u16, write_u16, 5);
+impl_integer!(u32, i32, u32, write_u32, 10);
+impl_integer!(u64, i64, u64, write_u64, 20);
+
+#[cfg(target_pointer_width = "16")]
+impl_integer!(usize, isize, u16, write_u16, 6);
+
+#[cfg(target_pointer_width = "32")]
+impl_integer!(usize, isize, u32, write_u32, 11);
+
+#[cfg(target_pointer_width = "64")]
+impl_integer!(usize, isize, u64, write_u64, 20);
+
+mod tests {
+    // comprehenisive test
+    #[test]
+    fn test_i8_all() {
+        use super::Integer;
+        let mut buf = Vec::with_capacity(i8::MAX_LEN);
+
+        for n in i8::MIN..=i8::MAX {
+            unsafe {
+                let l = n.write_to(buf.as_mut_ptr());
+                buf.set_len(l);
+                assert_eq!(std::str::from_utf8_unchecked(&*buf), format!("{}", n));
+            }
+        }
+    }
+
+    // random test
+    #[test]
+    fn test_u64_random() {
+        use super::Integer;
+        let mut buf = Vec::with_capacity(u64::MAX_LEN);
+
+        let mut state = 88172645463325252u64;
+
+        for _ in 0..100 {
+            // xorshift
+            state ^= state << 13;
+            state ^= state >> 7;
+            state ^= state << 17;
+
+            unsafe {
+                let l = state.write_to(buf.as_mut_ptr());
+                buf.set_len(l);
+                assert_eq!(std::str::from_utf8_unchecked(&*buf), format!("{}", state));
+            }
+        }
+    }
+
+    macro_rules! make_test {
+        ($name:ident, $type:ty, $($value:expr),*) => {
+            #[test]
+            fn $name() {
+                use super::Integer;
+
+                let mut buf = Vec::with_capacity(<$type>::MAX_LEN);
+                $(
+                    unsafe {
+                        let l = ($value as $type).write_to(buf.as_mut_ptr());
+                        buf.set_len(l);
+                        assert_eq!(
+                            std::str::from_utf8_unchecked(&*buf),
+                            format!("{}", $value as $type)
+                        );
+                    }
+                )*
+            }
+        }
+    }
+
+    // boundary tests
+    make_test!(test_u8, u8, 0, 1, 9, 10, 99, 100, 254, 255);
+    make_test!(test_u16, u16, 0, 9, 10, 99, 100, 999, 1000, 9999, 10000, 65535);
+    make_test!(
+        test_u32, u32, 0, 9, 10, 99, 100, 999, 1000, 9999, 10000, 99999, 100000, 999999,
+        1000000, 9999999, 10000000, 99999999, 100000000, 999999999, 1000000000,
+        4294967295
+    );
+    make_test!(
+        test_u64,
+        u64,
+        0,
+        9,
+        10,
+        99,
+        100,
+        999,
+        1000,
+        9999,
+        10000,
+        99999,
+        100000,
+        999999,
+        1000000,
+        9999999,
+        10000000,
+        99999999,
+        100000000,
+        999999999,
+        1000000000,
+        9999999999,
+        10000000000,
+        99999999999,
+        100000000000,
+        999999999999,
+        1000000000000,
+        9999999999999,
+        10000000000000,
+        99999999999999,
+        100000000000000,
+        999999999999999,
+        1000000000000000,
+        9999999999999999,
+        10000000000000000,
+        99999999999999999,
+        100000000000000000,
+        999999999999999999,
+        1000000000000000000,
+        9999999999999999999,
+        10000000000000000000,
+        18446744073709551615
+    );
+
+    make_test!(test_i8, i8, i8::MIN, i8::MAX);
+    make_test!(test_i16, i16, i16::MIN, i16::MAX);
+    make_test!(test_i32, i32, i32::MIN, i32::MAX);
+    make_test!(test_i64, i64, i64::MIN, i64::MAX);
+}
diff --git a/sailfish/src/runtime/mod.rs b/sailfish/src/runtime/mod.rs
index 1b6785f..0e3c161 100644
--- a/sailfish/src/runtime/mod.rs
+++ b/sailfish/src/runtime/mod.rs
@@ -2,6 +2,7 @@
 
 mod buffer;
 pub mod escape;
+mod integer;
 mod macros;
 mod render;
 mod size_hint;