ia-32_volume1_basic-arch

Addsd subsd mulsd divsd condition rounded result

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Unformatted text preview: on function returns RAISE_EXCEPTION to the filter function if an exception has to be raised (the exception_cause field indicates the cause). Otherwise, the emulation function returns DO_NOT_ RAISE_EXCEPTION. In the first case, the result is provided by the user exception handler called by the filter function. In the second case, it is provided by the emulation function. The filter function has to collect all the partial results, and to assemble the scalar or packed result that is used if execution is to continue. E-22 Vol. 1 GUIDELINES FOR WRITING SIMD FLOATING-POINT EXCEPTION HANDLERS Example E-1. SIMD Floating-Point Emulation // masks for individual status word bits #define PRECISION_MASK 0x20 #define UNDERFLOW_MASK 0x10 #define OVERFLOW_MASK 0x08 #define ZERODIVIDE_MASK 0x04 #define DENORMAL_MASK 0x02 #define INVALID_MASK 0x01 // 32-bit constants static unsigned ZEROF_ARRAY = {0x00000000}; #define ZEROF *(float *) ZEROF_ARRAY // +0.0 static unsigned NZEROF_ARRAY = {0x80000000}; #define NZEROF *(float *) NZEROF_ARRAY // -0.0 static unsigned POSINFF_ARRAY = {0x7f800000}; #define POSINFF *(float *)POSINFF_ARRAY // +Inf static unsigned NEGINFF_ARRAY = {0xff800000}; #define NEGINFF *(float *)NEGINFF_ARRAY // -Inf // 64-bit constants static unsigned MIN_SINGLE_NORMAL_ARRAY = {0x00000000, 0x38100000}; #define MIN_SINGLE_NORMAL *(double *)MIN_SINGLE_NORMAL_ARRAY // +1.0 * 2^-126 static unsigned MAX_SINGLE_NORMAL_ARRAY = {0x70000000, 0x47efffff}; #define MAX_SINGLE_NORMAL *(double *)MAX_SINGLE_NORMAL_ARRAY // +1.1...1*2^127 static unsigned TWO_TO_192_ARRAY = {0x00000000, 0x4bf00000}; #define TWO_TO_192 *(double *)TWO_TO_192_ARRAY // +1.0 * 2^192 static unsigned TWO_TO_M192_ARRAY = {0x00000000, 0x33f00000}; #define TWO_TO_M192 *(double *)TWO_TO_M192_ARRAY // +1.0 * 2^-192 // auxiliary functions static int isnanf (unsigned int ); // returns 1 if f is a NaN, and 0 otherwise static float quietf (unsigned int ); // converts a signaling NaN to a quiet // NaN, and leaves a quiet NaN unchanged static unsigned int check_for_daz (unsigned int ); // converts denormals // to zeros of the same sign; // does not affect any status flags // emulation of SSE and SSE2 instructions using // C code and x87 FPU instructions unsigned int simd_fp_emulate (EXC_ENV *exc_env) { Vol. 1 E-23 GUIDELINES FOR WRITING SIMD FLOATING-POINT EXCEPTION HANDLERS int uiopd1; // first operand of the add, subtract, multiply, or divide int uiopd2; // second operand of the add, subtract, multiply, or divide float res; // result of the add, subtract, multiply, or divide double dbl_res24; // result with 24-bit significand, but "unbounded" exponent // (needed to check tininess, to provide a scaled result to // an underflow/overflow trap handler, and in flush-to-zero mode) double dbl_res; // result in double precision format (needed to avoid a // double rounding error when denormalizing) unsigned int result_tiny; unsigned int result_huge; unsigned short int sw; // 16 bits unsigned short i...
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This note was uploaded on 10/01/2013 for the course CPE 103 taught by Professor Watlins during the Winter '11 term at Mississippi State.

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