diff options
Diffstat (limited to 'kernel/arch/x86/math-emu/reg_u_add.S')
| -rw-r--r-- | kernel/arch/x86/math-emu/reg_u_add.S | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/kernel/arch/x86/math-emu/reg_u_add.S b/kernel/arch/x86/math-emu/reg_u_add.S new file mode 100644 index 000000000..47c4c2434 --- /dev/null +++ b/kernel/arch/x86/math-emu/reg_u_add.S @@ -0,0 +1,167 @@ + .file "reg_u_add.S" +/*---------------------------------------------------------------------------+ + | reg_u_add.S | + | | + | Add two valid (TAG_Valid) FPU_REG numbers, of the same sign, and put the | + | result in a destination FPU_REG. | + | | + | Copyright (C) 1992,1993,1995,1997 | + | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia | + | E-mail billm@suburbia.net | + | | + | Call from C as: | + | int FPU_u_add(FPU_REG *arg1, FPU_REG *arg2, FPU_REG *answ, | + | int control_w) | + | Return value is the tag of the answer, or-ed with FPU_Exception if | + | one was raised, or -1 on internal error. | + | | + +---------------------------------------------------------------------------*/ + +/* + | Kernel addition routine FPU_u_add(reg *arg1, reg *arg2, reg *answ). + | Takes two valid reg f.p. numbers (TAG_Valid), which are + | treated as unsigned numbers, + | and returns their sum as a TAG_Valid or TAG_Special f.p. number. + | The returned number is normalized. + | Basic checks are performed if PARANOID is defined. + */ + +#include "exception.h" +#include "fpu_emu.h" +#include "control_w.h" + +.text +ENTRY(FPU_u_add) + pushl %ebp + movl %esp,%ebp + pushl %esi + pushl %edi + pushl %ebx + + movl PARAM1,%esi /* source 1 */ + movl PARAM2,%edi /* source 2 */ + + movl PARAM6,%ecx + movl %ecx,%edx + subl PARAM7,%ecx /* exp1 - exp2 */ + jge L_arg1_larger + + /* num1 is smaller */ + movl SIGL(%esi),%ebx + movl SIGH(%esi),%eax + + movl %edi,%esi + movl PARAM7,%edx + negw %cx + jmp L_accum_loaded + +L_arg1_larger: + /* num1 has larger or equal exponent */ + movl SIGL(%edi),%ebx + movl SIGH(%edi),%eax + +L_accum_loaded: + movl PARAM3,%edi /* destination */ + movw %dx,EXP(%edi) /* Copy exponent to destination */ + + xorl %edx,%edx /* clear the extension */ + +#ifdef PARANOID + testl $0x80000000,%eax + je L_bugged + + testl $0x80000000,SIGH(%esi) + je L_bugged +#endif /* PARANOID */ + +/* The number to be shifted is in %eax:%ebx:%edx */ + cmpw $32,%cx /* shrd only works for 0..31 bits */ + jnc L_more_than_31 + +/* less than 32 bits */ + shrd %cl,%ebx,%edx + shrd %cl,%eax,%ebx + shr %cl,%eax + jmp L_shift_done + +L_more_than_31: + cmpw $64,%cx + jnc L_more_than_63 + + subb $32,%cl + jz L_exactly_32 + + shrd %cl,%eax,%edx + shr %cl,%eax + orl %ebx,%ebx + jz L_more_31_no_low /* none of the lowest bits is set */ + + orl $1,%edx /* record the fact in the extension */ + +L_more_31_no_low: + movl %eax,%ebx + xorl %eax,%eax + jmp L_shift_done + +L_exactly_32: + movl %ebx,%edx + movl %eax,%ebx + xorl %eax,%eax + jmp L_shift_done + +L_more_than_63: + cmpw $65,%cx + jnc L_more_than_64 + + movl %eax,%edx + orl %ebx,%ebx + jz L_more_63_no_low + + orl $1,%edx + jmp L_more_63_no_low + +L_more_than_64: + movl $1,%edx /* The shifted nr always at least one '1' */ + +L_more_63_no_low: + xorl %ebx,%ebx + xorl %eax,%eax + +L_shift_done: + /* Now do the addition */ + addl SIGL(%esi),%ebx + adcl SIGH(%esi),%eax + jnc L_round_the_result + + /* Overflow, adjust the result */ + rcrl $1,%eax + rcrl $1,%ebx + rcrl $1,%edx + jnc L_no_bit_lost + + orl $1,%edx + +L_no_bit_lost: + incw EXP(%edi) + +L_round_the_result: + jmp fpu_reg_round /* Round the result */ + + + +#ifdef PARANOID +/* If we ever get here then we have problems! */ +L_bugged: + pushl EX_INTERNAL|0x201 + call EXCEPTION + pop %ebx + movl $-1,%eax + jmp L_exit + +L_exit: + popl %ebx + popl %edi + popl %esi + leave + ret +#endif /* PARANOID */ |