floating point environment/exceptions support for mips

arch/mips/bits/fenv.h

@@ -1,10 +1,20 @@
-#define FE_ALL_EXCEPT 0
+#define FE_INEXACT    4
-#define FE_TONEAREST  0
+#define FE_UNDERFLOW  8
+#define FE_OVERFLOW   16
+#define FE_DIVBYZERO  32
+#define FE_INVALID    64
 
-typedef unsigned long fexcept_t;
+#define FE_ALL_EXCEPT 124
+
+#define FE_TONEAREST  0
+#define FE_TOWARDZERO 1
+#define FE_UPWARD     2
+#define FE_DOWNWARD   3
+
+typedef unsigned short fexcept_t;
 
 typedef struct {
-	unsigned long __cw;
+	unsigned __cw;
 } fenv_t;
 
 #define FE_DFL_ENV      ((const fenv_t *) -1)

src/fenv/mips/fenv.s

@@ -0,0 +1,60 @@
+.set noreorder
+
+.global feclearexcept
+.type  feclearexcept,@function
+feclearexcept:
+	cfc1    $5, $31
+	or      $5, $5, $4
+	xor     $5, $5, $4
+	ctc1    $5, $31
+	jr      $ra
+	li      $2, 0
+
+.global feraiseexcept
+.type  feraiseexcept,@function
+feraiseexcept:
+	cfc1    $5, $31
+	or      $5, $5, $4
+	ctc1    $5, $31
+	jr      $ra
+	li      $2, 0
+
+.global fetestexcept
+.type  fetestexcept,@function
+fetestexcept:
+	cfc1    $2, $31
+	jr      $ra
+	and     $2, $2, $4
+
+.global fegetround
+.type  fegetround,@function
+fegetround:
+	cfc1    $2, $31
+	jr      $ra
+	andi    $2, $2, 3
+
+.global fesetround
+.type  fesetround,@function
+fesetround:
+	cfc1    $5, $31
+	li      $6, -4
+	and     $5, $5, $6
+	or      $5, $5, $4
+	jr      $ra
+	li      $2, 0
+
+.global fegetenv
+.type  fegetenv,@function
+fegetenv:
+	cfc1    $5, $31
+	sw      $5, 0($4)
+	jr      $ra
+	li      $2, 0
+
+.global fesetenv
+.type  fesetenv,@function
+fesetenv:
+	lw      $5, 0($4)
+	ctc1    $5, $31
+	jr      $ra
+	li      $2, 0