Florent DEFAY wrote:
My target machine doesn't support floats operations
> so I defined these macros :
#define TARGET_FLOAT_FORMAT IEEE_FLOAT_FORMAT #undef TARGET_DECIMAL_FLOAT_SUPPORTED_P #define TARGET_DECIMAL_FLOAT_SUPPORTED_P target_decimal_float_supported_p // returns always false #undef TARGET_FIXED_POINT_SUPPORTED_P #define TARGET_FIXED_POINT_SUPPORTED_P target_fixed_point_supported_p // returns always false and that's all about floats. What should I additionally implement ?
The normal way with no-FPU CPUs seems to be to use the 'config/fp-bit.c' which implements the basic soft-float routines in C. These routines then will be a part of the 'libgcc.a', the "GCC helper library". Another way is to implement these in the opsys kernel like in x86 with the old i386, i486SX, "embedded x86" etc. "no-*87 FPU inside" CPUs in the Linux kernel. The idea being that there could be that FPU in the system but when there isn't, every float opcode causes a "trap" or "exception" which the opsys kernel will handle... Third way is to implement the soft-float ops in the C library, I remember in Linux/PPC this being the case, the 'glibc' for it includes the soft-float operations. But with embedded "no FPU anywhere" CPUs the 'libgcc.a' normally has those basic soft-float routines for add/sub/mul/div for floats and doubles... Just "spy" the already ported CPUs, their "target Makefile-fragments", the 't-<cpu>' or something files in 'gcc/config/<cpu>'...
