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