Merge pull request #44 from futurecore/fix_print_large_float_crash

Deal explicitly with fix(NaN).

revelation/execute_farith.py

@@ -1,12 +1,140 @@
-from revelation.utils import bits2float, float2bits, get_exponent_as_decimal, trim_32
+from revelation.utils import bits2float, float2bits, get_exponent_as_decimal, is_nan, trim_32
 from pydgin.utils import signed
 
 import revelation.isa
 
-import math
+
+def make_float_executor(is16bit):
+    def exec_float(s, inst):
+        """
+        RD = float(RN)
+        BN = RD[31]
+        if (RD[30:0] == 0) { BZ=1 } else { BZ=0 }
+        if (UnbiasedExponent(RD) > 127) { BV=1 } else { BV=0 }
+        if (UbiasedExponent(RD) < -126) { BUS=1 } else { BUS=BUS }
+        if (RM or RN == NAN) { BIS=1 } else { BIS=BIS }
+        BVS = BVS | BV;
+
+        Corner cases: Overflow returns positive / negative infinity
+        (round-to-nearest), underflow returns positive / negative zero.
+        """
+        if is16bit:
+            inst.bits &= 0xffff
+        rn = signed(s.rf[inst.rn])
+        result = float(rn)
+        result_bits = float2bits(result)
+        # RD = RN <OP> RM
+        s.rf[inst.rd] = trim_32(result_bits)
+        # BN = RD[31]
+        s.BN = bool((result_bits >> 31) & 1)
+        # if (RD[30:0] == 0) { BZ=1 } else { BZ=0 }
+        s.BZ = True if abs(result) < 0.0001 else False
+        # if (UnbiasedExponent(RD) > 127) { BV=1 } else { BV=0 }
+        s.BV = True if get_exponent_as_decimal(s.rf[inst.rd]) > 127 else False
+        # if (UbiasedExponent(RD) < -126) { BUS=1 } else { BUS=BUS }
+        if get_exponent_as_decimal(s.rf[inst.rd]) < -126:
+            s.BUS = True
+        # BVS = BVS | BV;
+        s.BVS = s.BVS | s.BV
+        # No exceptions for float instruction.
+        if s.CTIMER0CONFIG == s.timer_config['FPU VALID'] and not s.BIS:
+            s.rf[revelation.isa.reg_map['CTIMER0']] -= 1
+        if s.CTIMER1CONFIG == s.timer_config['FPU VALID'] and not s.BIS:
+            s.rf[revelation.isa.reg_map['CTIMER1']] -= 1
+        s.debug_flags()
+        s.pc += 2 if is16bit else 4
+    return exec_float
+
+
+def make_fix_executor(is16bit):
+    def exec_fix(s, inst):
+        """
+        RD = fix(RN)
+        BN = RD[31]
+        if (RD[30:0] == 0) { BZ=1 } else { BZ=0 }
+        if (UnbiasedExponent(RD) > 127) { BV=1 } else { BV=0 }
+        if (UbiasedExponent(RD) < -126) { BUS=1 } else { BUS=BUS }
+        if (RM or RN == NAN) { BIS=1 } else { BIS=BIS }
+        BVS = BVS | BV;
+
+        Corner cases: A NAN input returns a floating-point all ones result. All
+        underflow results, or input which are zero or denormal, return zero.
+        Overflow result always returns a signed saturated result: 0x7fffffff for
+        positive, and 0x80000000 for negative.
+        """
+        if is16bit:
+            inst.bits &= 0xffff
+        rn = bits2float(s.rf[inst.rn])
+        if is_nan(s.rf[inst.rn]):
+            result = 0xffffffff
+        else:
+            result = int(rn)
+        if result != trim_32(result) and result > 0:  # Overflow (positive)
+            result = 0x7fffffff
+        if result != trim_32(result) and result < 0:  # Overflow (negative)
+            result = 0x80000000
+        # RD = RN <OP> RM
+        s.rf[inst.rd] = result
+        # BN = RD[31]
+        s.BN = bool((result >> 31) & 1)
+        # if (RD[30:0] == 0) { BZ=1 } else { BZ=0 }
+        s.BZ = True if abs(result) < 0.0001 else False
+        # if (UnbiasedExponent(RD) > 127) { BV=1 } else { BV=0 }
+        s.BV = True if get_exponent_as_decimal(s.rf[inst.rd]) > 127 else False
+        # if (UbiasedExponent(RD) < -126) { BUS=1 } else { BUS=BUS }
+        if get_exponent_as_decimal(s.rf[inst.rd]) < -126:
+            s.BUS = True
+        # BVS = BVS | BV;
+        s.BVS = s.BVS | s.BV
+        # FIXME: Find out whether fix generates interrupts.
+        if s.CTIMER0CONFIG == s.timer_config['FPU VALID'] and not s.BIS:
+            s.rf[revelation.isa.reg_map['CTIMER0']] -= 1
+        if s.CTIMER1CONFIG == s.timer_config['FPU VALID'] and not s.BIS:
+            s.rf[revelation.isa.reg_map['CTIMER1']] -= 1
+        s.debug_flags()
+        s.pc += 2 if is16bit else 4
+    return exec_fix
+
+
+def make_fabs_executor(is16bit):
+    def exec_fabs(s, inst):
+        """
+        RD = abs(RN)
+        BN = RD[31]
+        if (RD[30:0] == 0) { BZ=1 } else { BZ=0 }
+        if (UnbiasedExponent(RD) > 127) { BV=1 } else { BV=0 }
+        if (UbiasedExponent(RD) < -126) { BUS=1 } else { BUS=BUS }
+        if (RM or RN == NAN) { BIS=1 } else { BIS=BIS }
+        BVS = BVS | BV;
+        """
+        if is16bit:
+            inst.bits &= 0xffff
+        rn = bits2float(s.rf[inst.rn])
+        result = abs(rn)
+        # 'result' is always a Python float, result_bits is an int.
+        result_bits = float2bits(result)
+        # RD = RN <OP> RM
+        s.rf[inst.rd] = trim_32(result_bits)
+        # BN = RD[31]
+        s.BN = bool((result_bits >> 31) & 1)
+        # if (RD[30:0] == 0) { BZ=1 } else { BZ=0 }
+        s.BZ = True if abs(result) < 0.0001 else False
+        # if (RM or RN == NAN) { BIS=1 } else { BIS=BIS }
+        if is_nan(s.rf[inst.rn]):
+            s.BIS = True
+        # BVS = BVS | BV;
+        s.BVS = s.BVS | s.BV
+        # Deal with fpu interrupts.
+        if s.CTIMER0CONFIG == s.timer_config['FPU VALID'] and not s.BIS:
+            s.rf[revelation.isa.reg_map['CTIMER0']] -= 1  # pragma: no cover
+        if s.CTIMER1CONFIG == s.timer_config['FPU VALID'] and not s.BIS:
+            s.rf[revelation.isa.reg_map['CTIMER1']] -= 1  # pragma: no cover
+        s.debug_flags()
+        s.pc += 2 if is16bit else 4
+    return exec_fabs
 
 
-def make_farith_executor(name, is16bit, is_unary=False):
+def make_farith_executor(name, is16bit):
     def farith(s, inst):
         """
         RD = RN <OP> RM
@@ -24,7 +152,6 @@ def farith(s, inst):
             rd = bits2float(s.rf[inst.rd])
             rn = bits2float(s.rf[inst.rn])
             rm = bits2float(s.rf[inst.rm])
-            # Binary operations.
             if name == 'add':      # FADD
                 result = rn + rm
             elif name == 'sub':    # FSUB
@@ -35,17 +162,7 @@ def farith(s, inst):
                 result = rd + (rn * rm)
             elif name == 'msub':   # FMSUB
                 result = rd - (rn * rm)
-            # Unary operations.
-            elif name == 'float':  # FLOAT
-                result = float(signed(s.rf[inst.rn]))
-            elif name == 'fix':    # FIX
-                if math.isnan(rn):
-                    result = 0xffffffff
-                else:
-                    result = int(rn)
-            elif name == 'abs':    # FABS
-                result = abs(rn)
-            # 'result' is always a Python float, result_bits is an int.
+            # 'result' is a Python float, result_bits is a signed integer.
             result_bits = float2bits(result)
             # RD = RN <OP> RM
             s.rf[inst.rd] = trim_32(result if name == 'fix' else result_bits)
@@ -59,9 +176,7 @@ def farith(s, inst):
             if get_exponent_as_decimal(s.rf[inst.rd]) < -126:
                 s.BUS = True
             # if (RM or RN == NAN) { BIS=1 } else { BIS=BIS }
-            if ((is_unary and math.isnan(rn)) or
-                    (not is_unary) and
-                    (math.isnan(rn) or math.isnan(rm))):
+            if is_nan(s.rf[inst.rn]) or is_nan(s.rf[inst.rm]):
                 s.BIS = True
             # BVS = BVS | BV;
             s.BVS = s.BVS | s.BV

revelation/isa.py

@@ -219,17 +219,17 @@
 execute_fmul16  = execute_farith.make_farith_executor('mul', True)
 execute_fmadd16 = execute_farith.make_farith_executor('madd', True)
 execute_fmsub16 = execute_farith.make_farith_executor('msub', True)
-execute_float16 = execute_farith.make_farith_executor('float', True)
-execute_fix16   = execute_farith.make_farith_executor('fix', True)
-execute_fabs16  = execute_farith.make_farith_executor('abs', True)
+execute_float16 = execute_farith.make_float_executor(True)
+execute_fix16   = execute_farith.make_fix_executor(True)
+execute_fabs16  = execute_farith.make_fabs_executor(True)
 execute_fadd32  = execute_farith.make_farith_executor('add', False)
 execute_fsub32  = execute_farith.make_farith_executor('sub', False)
 execute_fmul32  = execute_farith.make_farith_executor('mul', False)
 execute_fmadd32 = execute_farith.make_farith_executor('madd', False)
 execute_fmsub32 = execute_farith.make_farith_executor('msub', False)
-execute_float32 = execute_farith.make_farith_executor('float', False)
-execute_fix32   = execute_farith.make_farith_executor('fix', False)
-execute_fabs32  = execute_farith.make_farith_executor('abs', False)
+execute_float32 = execute_farith.make_float_executor(False)
+execute_fix32   = execute_farith.make_fix_executor(False)
+execute_fabs32  = execute_farith.make_fabs_executor(False)
 
 # Move instructions
 execute_movcond32 = execute_mov.make_movcond_executor(False)

revelation/test/c/float_corner_cases.c

@@ -0,0 +1,16 @@
+/* Some floating point corner cases. */
+#include <float.h>
+#include <stdio.h>
+#include <stdint.h>
+
+int main() {
+    int val_i = 0xffffffff;
+    float val_f = 0xffffffff;
+    float convert_f = (float)val_i;
+    int convert_i = (int)val_f;
+    printf("Signed integer value = %d, %x\n", val_i, val_i);
+    printf("Float value = %.*e\n", DECIMAL_DIG, val_f);
+    printf("Convert float to signed integer: %d, %x\n", convert_i, convert_i);
+    printf("Convert signed integer to float = %.*e\n", DECIMAL_DIG, convert_f);
+    return 0;
+}

revelation/test/c/interrupt_ctimer0.c

@@ -1,4 +1,5 @@
 #include <e-lib.h>
+#include <math.h>
 #include <stdio.h>
 
 void timer_handler();
@@ -9,7 +10,7 @@ void __attribute__((interrupt)) timer_handler() {
 
 int main() {
     float a = 1., b = 2., c = 0.;
-    int i = 0;
+    int i = 0, d = 0;
 
     /* Attach and set-up timer interrupt. */
     e_irq_attach(E_TIMER0_INT, timer_handler);
@@ -21,7 +22,8 @@ int main() {
     e_ctimer_start(E_CTIMER_0, E_CTIMER_FPU_INST);
 
     for (i = 0; i < 15; i++) {
-        c = a + b;
+        c = fabs(a + b + (float)d);
+        d = (int)c;
     }
     /* Interrupt should be triggered here. */
 

revelation/test/c/interrupt_ctimer1.c

@@ -1,4 +1,5 @@
 #include <e-lib.h>
+#include <math.h>
 #include <stdio.h>
 
 void timer_handler();
@@ -9,7 +10,7 @@ void __attribute__((interrupt)) timer_handler() {
 
 int main() {
     float a = 1., b = 2., c = 0.;
-    int i = 0;
+    int i = 0, d = 0;
 
     /* Attach and set-up timer interrupt. */
     e_irq_attach(E_TIMER1_INT, timer_handler);
@@ -21,7 +22,8 @@ int main() {
     e_ctimer_start(E_CTIMER_1, E_CTIMER_FPU_INST);
 
     for (i = 0; i < 15; i++) {
-        c = a + b;
+        c = fabs(a + b + (float)d);
+        d = (int)c;
     }
     /* Interrupt should be triggered here. */
 

revelation/test/test_compiled_c.py

@@ -16,6 +16,11 @@
      ('div_by_zero.elf',        'Exception_isr 214023\nEnd.\n'),
      ('get_core_coords.elf',    'Core id: 808 row=32 col=8\n'),
      ('fib_print.elf',          '10946\n'),
+     ('float_corner_cases.elf', 'Signed integer value = -1, ffffffff\n'
+                                'Float value = 4.29496729600000000e+09\n'
+                                'Convert float to signed integer: 2147483647,'
+                                ' 7fffffff\nConvert signed integer to float ='
+                                ' -1.00000000000000000e+00\n'),
      ('hello.elf',              'Hello, world!\n'),
      ('interrupt_fire_all.elf', 'Interrupt E_SW_EXCEPTION ... handler fired.\n'
                                 'Interrupt E_MEM_FAULT    ... handler fired.\n'