Implement IEEE Std 754-2008 non-arithmetic ABS.fmt and NEG.fmt emulation wired to the state of the FCSR.ABS2008 bit. In the non-arithmetic mode the sign bit is altered according to the operation requested regardless of the datum encoded in the input operand, no other bits are changed, the resulting bit pattern is written to the output operand and no exception is ever signalled.
Signed-off-by: Maciej W. Rozycki <[email protected]> --- linux-mips-emu-abs2008.diff Index: linux-sfr-test/arch/mips/math-emu/dp_simple.c =================================================================== --- linux-sfr-test.orig/arch/mips/math-emu/dp_simple.c 2015-11-10 17:45:25.145419000 +0000 +++ linux-sfr-test/arch/mips/math-emu/dp_simple.c 2015-11-11 02:19:59.120054000 +0000 @@ -23,27 +23,39 @@ union ieee754dp ieee754dp_neg(union ieee754dp x) { - unsigned int oldrm; union ieee754dp y; - oldrm = ieee754_csr.rm; - ieee754_csr.rm = FPU_CSR_RD; - y = ieee754dp_sub(ieee754dp_zero(0), x); - ieee754_csr.rm = oldrm; + if (ieee754_csr.abs2008) { + y = x; + DPSIGN(y) = !DPSIGN(x); + } else { + unsigned int oldrm; + + oldrm = ieee754_csr.rm; + ieee754_csr.rm = FPU_CSR_RD; + y = ieee754dp_sub(ieee754dp_zero(0), x); + ieee754_csr.rm = oldrm; + } return y; } union ieee754dp ieee754dp_abs(union ieee754dp x) { - unsigned int oldrm; union ieee754dp y; - oldrm = ieee754_csr.rm; - ieee754_csr.rm = FPU_CSR_RD; - if (DPSIGN(x)) - y = ieee754dp_sub(ieee754dp_zero(0), x); - else - y = ieee754dp_add(ieee754dp_zero(0), x); - ieee754_csr.rm = oldrm; + if (ieee754_csr.abs2008) { + y = x; + DPSIGN(y) = 0; + } else { + unsigned int oldrm; + + oldrm = ieee754_csr.rm; + ieee754_csr.rm = FPU_CSR_RD; + if (DPSIGN(x)) + y = ieee754dp_sub(ieee754dp_zero(0), x); + else + y = ieee754dp_add(ieee754dp_zero(0), x); + ieee754_csr.rm = oldrm; + } return y; } Index: linux-sfr-test/arch/mips/math-emu/sp_simple.c =================================================================== --- linux-sfr-test.orig/arch/mips/math-emu/sp_simple.c 2015-11-10 17:45:25.147428000 +0000 +++ linux-sfr-test/arch/mips/math-emu/sp_simple.c 2015-11-11 02:19:59.165062000 +0000 @@ -23,27 +23,39 @@ union ieee754sp ieee754sp_neg(union ieee754sp x) { - unsigned int oldrm; union ieee754sp y; - oldrm = ieee754_csr.rm; - ieee754_csr.rm = FPU_CSR_RD; - y = ieee754sp_sub(ieee754sp_zero(0), x); - ieee754_csr.rm = oldrm; + if (ieee754_csr.abs2008) { + y = x; + SPSIGN(y) = !SPSIGN(x); + } else { + unsigned int oldrm; + + oldrm = ieee754_csr.rm; + ieee754_csr.rm = FPU_CSR_RD; + y = ieee754sp_sub(ieee754sp_zero(0), x); + ieee754_csr.rm = oldrm; + } return y; } union ieee754sp ieee754sp_abs(union ieee754sp x) { - unsigned int oldrm; union ieee754sp y; - oldrm = ieee754_csr.rm; - ieee754_csr.rm = FPU_CSR_RD; - if (SPSIGN(x)) - y = ieee754sp_sub(ieee754sp_zero(0), x); - else - y = ieee754sp_add(ieee754sp_zero(0), x); - ieee754_csr.rm = oldrm; + if (ieee754_csr.abs2008) { + y = x; + SPSIGN(y) = 0; + } else { + unsigned int oldrm; + + oldrm = ieee754_csr.rm; + ieee754_csr.rm = FPU_CSR_RD; + if (SPSIGN(x)) + y = ieee754sp_sub(ieee754sp_zero(0), x); + else + y = ieee754sp_add(ieee754sp_zero(0), x); + ieee754_csr.rm = oldrm; + } return y; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
