Add thread local softfloat_fp8Mode variable to control the 8 bit floating point format

Will eventaully be hooked up to architectural register to control toggel.

Author: rbuchner-aril

softfloat/softfloat.h

@@ -69,6 +69,16 @@ enum {
     softfloat_tininess_afterRounding  = 1
 };
 
+/*----------------------------------------------------------------------------
+| Software floating-point 8-bit mode.
+*----------------------------------------------------------------------------*/
+extern THREAD_LOCAL uint_fast8_t softfloat_fp8Mode;
+enum {
+    softfloat_fp8_8p5 = 0,
+    softfloat_fp8_8p4 = 1,
+    softfloat_fp8_8p3 = 2
+};
+
 /*----------------------------------------------------------------------------
 | Software floating-point rounding mode.  (Mode "odd" is supported only if
 | SoftFloat is compiled with macro 'SOFTFLOAT_ROUND_ODD' defined.)

softfloat/softfloat_state.c

@@ -44,6 +44,7 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #define THREAD_LOCAL
 #endif
 
+THREAD_LOCAL uint_fast8_t softfloat_fp8Mode = softfloat_fp8_8p5;
 THREAD_LOCAL uint_fast8_t softfloat_roundingMode = softfloat_round_near_even;
 THREAD_LOCAL uint_fast8_t softfloat_detectTininess = init_detectTininess;
 THREAD_LOCAL uint_fast8_t softfloat_exceptionFlags = 0;