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path: root/arch/nds32/math-emu/fpuemu.c
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2019-05-31nds32: add new emulations for floating point instructionVincent Chen
The existing floating point emulations is only available for floating instruction that possibly issue denormalized input and underflow exceptions. These existing FPU emulations are not sufficient when IEx Trap is enabled because some floating point instructions only issue inexact exception. This patch adds the emulations of such floating point instructions. Signed-off-by: Vincent Chen <vincentc@andestech.com> Acked-by: Greentime Hu <greentime@andestech.com> Signed-off-by: Greentime Hu <greentime@andestech.com>
2018-11-22nds32: support denormalized result through FP emulatorVincent Chen
Currently, the nds32 FPU dose not support the arithmetic of denormalized number. When the nds32 FPU finds the result of the instruction is a denormlized number, the nds32 FPU considers it to be an underflow condition and rounds the result to an appropriate number. It may causes some loss of precision. This commit proposes a solution to re-execute the instruction by the FPU emulator to enhance the precision. To transfer calculations from user space to kernel space, this feature will enable the underflow exception trap by default. Enabling this feature may cause some side effects: 1. Performance loss due to extra FPU exception 2. Need another scheme to control real underflow trap A new parameter, UDF_trap, which is belong to FPU context is used to control underflow trap. User can configure this feature via CONFIG_SUPPORT_DENORMAL_ARITHMETIC Signed-off-by: Vincent Chen <vincentc@andestech.com> Acked-by: Greentime Hu <greentime@andestech.com> Signed-off-by: Greentime Hu <greentime@andestech.com>
2018-11-22nds32: Support FP emulationVincent Chen
The Andes FPU coprocessor does not support denormalized number handling. According to the specification, FPU generates a denorm input exception that requires the kernel to deal with this instrution operation when it encounters denormalized operands. Hence an nds32 FPU ISA emulator in the kernel is required to meet requirement. Signed-off-by: Vincent Chen <vincentc@andestech.com> Signed-off-by: Nickhu <nickhu@andestech.com> Acked-by: Greentime Hu <greentime@andestech.com> Signed-off-by: Greentime Hu <greentime@andestech.com>