1 files changed, 126 insertions, 0 deletions
diff --git a/src/cmd/internal/obj/s390x/condition_code.go b/src/cmd/internal/obj/s390x/condition_code.go
new file mode 100644
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--- /dev/null
+++ b/src/cmd/internal/obj/s390x/condition_code.go
@@ -0,0 +1,126 @@
+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package s390x
+
+import (
+	"fmt"
+)
+
+// CCMask represents a 4-bit condition code mask. Bits that
+// are not part of the mask should be 0.
+//
+// Condition code masks represent the 4 possible values of
+// the 2-bit condition code as individual bits. Since IBM Z
+// is a big-endian platform bits are numbered from left to
+// right. The lowest value, 0, is represented by 8 (0b1000)
+// and the highest value, 3, is represented by 1 (0b0001).
+//
+// Note that condition code values have different semantics
+// depending on the instruction that set the condition code.
+// The names given here assume that the condition code was
+// set by an integer or floating point comparison. Other
+// instructions may use these same codes to indicate
+// different results such as a carry or overflow.
+type CCMask uint8
+
+const (
+	Never CCMask = 0 // no-op
+
+	// 1-bit masks
+	Equal     CCMask = 1 << 3
+	Less      CCMask = 1 << 2
+	Greater   CCMask = 1 << 1
+	Unordered CCMask = 1 << 0
+
+	// 2-bit masks
+	EqualOrUnordered   CCMask = Equal | Unordered   // not less and not greater
+	LessOrEqual        CCMask = Less | Equal        // ordered and not greater
+	LessOrGreater      CCMask = Less | Greater      // ordered and not equal
+	LessOrUnordered    CCMask = Less | Unordered    // not greater and not equal
+	GreaterOrEqual     CCMask = Greater | Equal     // ordered and not less
+	GreaterOrUnordered CCMask = Greater | Unordered // not less and not equal
+
+	// 3-bit masks
+	NotEqual     CCMask = Always ^ Equal
+	NotLess      CCMask = Always ^ Less
+	NotGreater   CCMask = Always ^ Greater
+	NotUnordered CCMask = Always ^ Unordered
+
+	// 4-bit mask
+	Always CCMask = Equal | Less | Greater | Unordered
+
+	// useful aliases
+	Carry    CCMask = GreaterOrUnordered
+	NoCarry  CCMask = LessOrEqual
+	Borrow   CCMask = NoCarry
+	NoBorrow CCMask = Carry
+)
+
+// Inverse returns the complement of the condition code mask.
+func (c CCMask) Inverse() CCMask {
+	return c ^ Always
+}
+
+// ReverseComparison swaps the bits at 0b0100 and 0b0010 in the mask,
+// reversing the behavior of greater than and less than conditions.
+func (c CCMask) ReverseComparison() CCMask {
+	r := c & EqualOrUnordered
+	if c&Less != 0 {
+		r |= Greater
+	}
+	if c&Greater != 0 {
+		r |= Less
+	}
+	return r
+}
+
+func (c CCMask) String() string {
+	switch c {
+	// 0-bit mask
+	case Never:
+		return "Never"
+
+	// 1-bit masks
+	case Equal:
+		return "Equal"
+	case Less:
+		return "Less"
+	case Greater:
+		return "Greater"
+	case Unordered:
+		return "Unordered"
+
+	// 2-bit masks
+	case EqualOrUnordered:
+		return "EqualOrUnordered"
+	case LessOrEqual:
+		return "LessOrEqual"
+	case LessOrGreater:
+		return "LessOrGreater"
+	case LessOrUnordered:
+		return "LessOrUnordered"
+	case GreaterOrEqual:
+		return "GreaterOrEqual"
+	case GreaterOrUnordered:
+		return "GreaterOrUnordered"
+
+	// 3-bit masks
+	case NotEqual:
+		return "NotEqual"
+	case NotLess:
+		return "NotLess"
+	case NotGreater:
+		return "NotGreater"
+	case NotUnordered:
+		return "NotUnordered"
+
+	// 4-bit mask
+	case Always:
+		return "Always"
+	}
+
+	// invalid
+	return fmt.Sprintf("Invalid (%#x)", c)
+}