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Diffstat (limited to 'arch/x86/math-emu/reg_norm.S')
-rw-r--r-- | arch/x86/math-emu/reg_norm.S | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/arch/x86/math-emu/reg_norm.S b/arch/x86/math-emu/reg_norm.S new file mode 100644 index 0000000000..594936eeed --- /dev/null +++ b/arch/x86/math-emu/reg_norm.S @@ -0,0 +1,150 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/*---------------------------------------------------------------------------+ + | reg_norm.S | + | | + | Copyright (C) 1992,1993,1994,1995,1997 | + | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, | + | Australia. E-mail billm@suburbia.net | + | | + | Normalize the value in a FPU_REG. | + | | + | Call from C as: | + | int FPU_normalize(FPU_REG *n) | + | | + | int FPU_normalize_nuo(FPU_REG *n) | + | | + | Return value is the tag of the answer, or-ed with FPU_Exception if | + | one was raised, or -1 on internal error. | + | | + +---------------------------------------------------------------------------*/ + +#include "fpu_emu.h" + + +.text +SYM_FUNC_START(FPU_normalize) + pushl %ebp + movl %esp,%ebp + pushl %ebx + + movl PARAM1,%ebx + + movl SIGH(%ebx),%edx + movl SIGL(%ebx),%eax + + orl %edx,%edx /* ms bits */ + js L_done /* Already normalized */ + jnz L_shift_1 /* Shift left 1 - 31 bits */ + + orl %eax,%eax + jz L_zero /* The contents are zero */ + + movl %eax,%edx + xorl %eax,%eax + subw $32,EXP(%ebx) /* This can cause an underflow */ + +/* We need to shift left by 1 - 31 bits */ +L_shift_1: + bsrl %edx,%ecx /* get the required shift in %ecx */ + subl $31,%ecx + negl %ecx + shld %cl,%eax,%edx + shl %cl,%eax + subw %cx,EXP(%ebx) /* This can cause an underflow */ + + movl %edx,SIGH(%ebx) + movl %eax,SIGL(%ebx) + +L_done: + cmpw EXP_OVER,EXP(%ebx) + jge L_overflow + + cmpw EXP_UNDER,EXP(%ebx) + jle L_underflow + +L_exit_valid: + movl TAG_Valid,%eax + + /* Convert the exponent to 80x87 form. */ + addw EXTENDED_Ebias,EXP(%ebx) + andw $0x7fff,EXP(%ebx) + +L_exit: + popl %ebx + leave + RET + + +L_zero: + movw $0,EXP(%ebx) + movl TAG_Zero,%eax + jmp L_exit + +L_underflow: + /* Convert the exponent to 80x87 form. */ + addw EXTENDED_Ebias,EXP(%ebx) + push %ebx + call arith_underflow + pop %ebx + jmp L_exit + +L_overflow: + /* Convert the exponent to 80x87 form. */ + addw EXTENDED_Ebias,EXP(%ebx) + push %ebx + call arith_overflow + pop %ebx + jmp L_exit +SYM_FUNC_END(FPU_normalize) + + + +/* Normalise without reporting underflow or overflow */ +SYM_FUNC_START(FPU_normalize_nuo) + pushl %ebp + movl %esp,%ebp + pushl %ebx + + movl PARAM1,%ebx + + movl SIGH(%ebx),%edx + movl SIGL(%ebx),%eax + + orl %edx,%edx /* ms bits */ + js L_exit_nuo_valid /* Already normalized */ + jnz L_nuo_shift_1 /* Shift left 1 - 31 bits */ + + orl %eax,%eax + jz L_exit_nuo_zero /* The contents are zero */ + + movl %eax,%edx + xorl %eax,%eax + subw $32,EXP(%ebx) /* This can cause an underflow */ + +/* We need to shift left by 1 - 31 bits */ +L_nuo_shift_1: + bsrl %edx,%ecx /* get the required shift in %ecx */ + subl $31,%ecx + negl %ecx + shld %cl,%eax,%edx + shl %cl,%eax + subw %cx,EXP(%ebx) /* This can cause an underflow */ + + movl %edx,SIGH(%ebx) + movl %eax,SIGL(%ebx) + +L_exit_nuo_valid: + movl TAG_Valid,%eax + + popl %ebx + leave + RET + +L_exit_nuo_zero: + movl TAG_Zero,%eax + movw EXP_UNDER,EXP(%ebx) + + popl %ebx + leave + RET +SYM_FUNC_END(FPU_normalize_nuo) |