[raw_ostream] Raise some helper functions out of raw_ostream.

Low level functionality to format numbers were embedded in the
implementation of raw_ostream.  I have need to use these through
an interface other than the overloaded stream operators, so they
need to be raised to a level that they can be used from either
raw_ostream operators or other code.

llvm-svn: 283921

1 files changed, 180 insertions, 0 deletions

diff --git a/llvm/lib/Support/NativeFormatting.cpp b/llvm/lib/Support/NativeFormatting.cpp
new file mode 100644
index 00000000000..84f6c390b02
--- /dev/null
+++ b/llvm/lib/Support/NativeFormatting.cpp
@@ -0,0 +1,180 @@
+//===- NativeFormatting.cpp - Low level formatting helpers -------*- C++-*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/NativeFormatting.h"
+
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/Format.h"
+
+using namespace llvm;
+
+template<typename T, std::size_t N>
+static int format_to_buffer(T Value, char (&Buffer)[N]) {
+  char *EndPtr = std::end(Buffer);
+  char *CurPtr = EndPtr;
+
+  while (Value) {
+    *--CurPtr = '0' + char(Value % 10);
+    Value /= 10;
+  }
+  return EndPtr - CurPtr;
+}
+
+void llvm::write_ulong(raw_ostream &S, unsigned long N, std::size_t MinWidth) {
+  // Zero is a special case.
+  if (N == 0) {
+    if (MinWidth > 0)
+      S.indent(MinWidth - 1);
+    S << '0';
+    return;
+  }
+
+  char NumberBuffer[20];
+  int Len = format_to_buffer(N, NumberBuffer);
+  int Pad = (MinWidth == 0) ? 0 : MinWidth - Len;
+  if (Pad > 0)
+    S.indent(Pad);
+  S.write(std::end(NumberBuffer) - Len, Len);
+}
+
+void llvm::write_long(raw_ostream &S, long N, std::size_t MinWidth) {
+  if (N >= 0) {
+    write_ulong(S, static_cast<unsigned long>(N), MinWidth);
+    return;
+  }
+
+  unsigned long UN = -(unsigned long)N;
+  if (MinWidth > 0)
+    --MinWidth;
+
+  char NumberBuffer[20];
+  int Len = format_to_buffer(UN, NumberBuffer);
+  int Pad = (MinWidth == 0) ? 0 : MinWidth - Len;
+  if (Pad > 0)
+    S.indent(Pad);
+  S.write('-');
+  S.write(std::end(NumberBuffer) - Len, Len);
+}
+
+void llvm::write_ulonglong(raw_ostream &S, unsigned long long N,
+                           std::size_t MinWidth) {
+  // Output using 32-bit div/mod when possible.
+  if (N == static_cast<unsigned long>(N)) {
+    write_ulong(S, static_cast<unsigned long>(N), MinWidth);
+    return;
+  }
+
+  char NumberBuffer[32];
+  int Len = format_to_buffer(N, NumberBuffer);
+  int Pad = (MinWidth == 0) ? 0 : MinWidth - Len;
+  if (Pad > 0)
+    S.indent(Pad);
+  S.write(std::end(NumberBuffer) - Len, Len);
+}
+
+void llvm::write_longlong(raw_ostream &S, long long N, std::size_t MinWidth) {
+  if (N >= 0) {
+    write_ulonglong(S, static_cast<unsigned long long>(N), MinWidth);
+    return;
+  }
+
+  // Avoid undefined behavior on INT64_MIN with a cast.
+  unsigned long long UN = -(unsigned long long)N;
+  if (MinWidth > 0)
+    --MinWidth;
+
+  char NumberBuffer[32];
+  int Len = format_to_buffer(UN, NumberBuffer);
+  int Pad = (MinWidth == 0) ? 0 : MinWidth - Len;
+  if (Pad > 0)
+    S.indent(Pad);
+  S.write('-');
+  S.write(std::end(NumberBuffer) - Len, Len);
+}
+
+void llvm::write_hex(raw_ostream &S, unsigned long long N, std::size_t MinWidth,
+                     bool Upper, bool Prefix) {
+  unsigned Nibbles = (64 - countLeadingZeros(N) + 3) / 4;
+  unsigned PrefixChars = Prefix ? 2 : 0;
+  unsigned Width = std::max(MinWidth, std::max(1u, Nibbles) + PrefixChars);
+
+  char NumberBuffer[20] = "0x0000000000000000";
+  if (!Prefix)
+    NumberBuffer[1] = '0';
+  char *EndPtr = NumberBuffer + Width;
+  char *CurPtr = EndPtr;
+  while (N) {
+    unsigned char x = static_cast<unsigned char>(N) % 16;
+    *--CurPtr = hexdigit(x, !Upper);
+    N /= 16;
+  }
+
+  S.write(NumberBuffer, Width);
+}
+
+void llvm::write_double(raw_ostream &S, double N, std::size_t MinWidth,
+                        std::size_t MinDecimals, FloatStyle Style) {
+  char Letter = (Style == FloatStyle::Exponent) ? 'e' : 'f';
+  SmallString<8> Spec;
+  llvm::raw_svector_ostream Out(Spec);
+  Out << '%';
+  if (MinWidth > 0)
+    Out << MinWidth;
+  if (MinDecimals > 0)
+    Out << '.' << MinDecimals;
+  Out << Letter;
+
+  if (Style == FloatStyle::Exponent) {
+#ifdef _WIN32
+// On MSVCRT and compatible, output of %e is incompatible to Posix
+// by default. Number of exponent digits should be at least 2. "%+03d"
+// FIXME: Implement our formatter to here or Support/Format.h!
+#if defined(__MINGW32__)
+    // FIXME: It should be generic to C++11.
+    if (N == 0.0 && std::signbit(N)) {
+      S << "-0.000000e+00";
+      return;
+    }
+#else
+    int fpcl = _fpclass(N);
+
+    // negative zero
+    if (fpcl == _FPCLASS_NZ) {
+      S << "-0.000000e+00";
+      return;
+    }
+#endif
+
+    char buf[16];
+    unsigned len;
+    len = format(Spec.c_str(), N).snprint(buf, sizeof(buf));
+    if (len <= sizeof(buf) - 2) {
+      if (len >= 5 && buf[len - 5] == 'e' && buf[len - 3] == '0') {
+        int cs = buf[len - 4];
+        if (cs == '+' || cs == '-') {
+          int c1 = buf[len - 2];
+          int c0 = buf[len - 1];
+          if (isdigit(static_cast<unsigned char>(c1)) &&
+              isdigit(static_cast<unsigned char>(c0))) {
+            // Trim leading '0': "...e+012" -> "...e+12\0"
+            buf[len - 3] = c1;
+            buf[len - 2] = c0;
+            buf[--len] = 0;
+          }
+        }
+      }
+      S << buf;
+      return;
+    }
+#endif
+  }
+
+  S << format(Spec.c_str(), N);
+}