diff options
Diffstat (limited to 'arch/i386/math-emu/reg_u_div.S')
| -rw-r--r-- | arch/i386/math-emu/reg_u_div.S | 471 |
1 files changed, 0 insertions, 471 deletions
diff --git a/arch/i386/math-emu/reg_u_div.S b/arch/i386/math-emu/reg_u_div.S deleted file mode 100644 index cc00654..0000000 --- a/arch/i386/math-emu/reg_u_div.S +++ /dev/null @@ -1,471 +0,0 @@ - .file "reg_u_div.S" -/*---------------------------------------------------------------------------+ - | reg_u_div.S | - | | - | Divide one FPU_REG by another 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_div(FPU_REG *a, FPU_REG *b, FPU_REG *dest, | - | unsigned int control_word, char *sign) | - | | - | Does not compute the destination exponent, but does adjust it. | - | | - | Return value is the tag of the answer, or-ed with FPU_Exception if | - | one was raised, or -1 on internal error. | - +---------------------------------------------------------------------------*/ - -#include "exception.h" -#include "fpu_emu.h" -#include "control_w.h" - - -/* #define dSIGL(x) (x) */ -/* #define dSIGH(x) 4(x) */ - - -#ifndef NON_REENTRANT_FPU -/* - Local storage on the stack: - Result: FPU_accum_3:FPU_accum_2:FPU_accum_1:FPU_accum_0 - Overflow flag: ovfl_flag - */ -#define FPU_accum_3 -4(%ebp) -#define FPU_accum_2 -8(%ebp) -#define FPU_accum_1 -12(%ebp) -#define FPU_accum_0 -16(%ebp) -#define FPU_result_1 -20(%ebp) -#define FPU_result_2 -24(%ebp) -#define FPU_ovfl_flag -28(%ebp) - -#else -.data -/* - Local storage in a static area: - Result: FPU_accum_3:FPU_accum_2:FPU_accum_1:FPU_accum_0 - Overflow flag: ovfl_flag - */ - .align 4,0 -FPU_accum_3: - .long 0 -FPU_accum_2: - .long 0 -FPU_accum_1: - .long 0 -FPU_accum_0: - .long 0 -FPU_result_1: - .long 0 -FPU_result_2: - .long 0 -FPU_ovfl_flag: - .byte 0 -#endif /* NON_REENTRANT_FPU */ - -#define REGA PARAM1 -#define REGB PARAM2 -#define DEST PARAM3 - -.text -ENTRY(FPU_u_div) - pushl %ebp - movl %esp,%ebp -#ifndef NON_REENTRANT_FPU - subl $28,%esp -#endif /* NON_REENTRANT_FPU */ - - pushl %esi - pushl %edi - pushl %ebx - - movl REGA,%esi - movl REGB,%ebx - movl DEST,%edi - - movswl EXP(%esi),%edx - movswl EXP(%ebx),%eax - subl %eax,%edx - addl EXP_BIAS,%edx - - /* A denormal and a large number can cause an exponent underflow */ - cmpl EXP_WAY_UNDER,%edx - jg xExp_not_underflow - - /* Set to a really low value allow correct handling */ - movl EXP_WAY_UNDER,%edx - -xExp_not_underflow: - - movw %dx,EXP(%edi) - -#ifdef PARANOID -/* testl $0x80000000, SIGH(%esi) // Dividend */ -/* je L_bugged */ - testl $0x80000000, SIGH(%ebx) /* Divisor */ - je L_bugged -#endif /* PARANOID */ - -/* Check if the divisor can be treated as having just 32 bits */ - cmpl $0,SIGL(%ebx) - jnz L_Full_Division /* Can't do a quick divide */ - -/* We should be able to zip through the division here */ - movl SIGH(%ebx),%ecx /* The divisor */ - movl SIGH(%esi),%edx /* Dividend */ - movl SIGL(%esi),%eax /* Dividend */ - - cmpl %ecx,%edx - setaeb FPU_ovfl_flag /* Keep a record */ - jb L_no_adjust - - subl %ecx,%edx /* Prevent the overflow */ - -L_no_adjust: - /* Divide the 64 bit number by the 32 bit denominator */ - divl %ecx - movl %eax,FPU_result_2 - - /* Work on the remainder of the first division */ - xorl %eax,%eax - divl %ecx - movl %eax,FPU_result_1 - - /* Work on the remainder of the 64 bit division */ - xorl %eax,%eax - divl %ecx - - testb $255,FPU_ovfl_flag /* was the num > denom ? */ - je L_no_overflow - - /* Do the shifting here */ - /* increase the exponent */ - incw EXP(%edi) - - /* shift the mantissa right one bit */ - stc /* To set the ms bit */ - rcrl FPU_result_2 - rcrl FPU_result_1 - rcrl %eax - -L_no_overflow: - jmp LRound_precision /* Do the rounding as required */ - - -/*---------------------------------------------------------------------------+ - | Divide: Return arg1/arg2 to arg3. | - | | - | This routine does not use the exponents of arg1 and arg2, but does | - | adjust the exponent of arg3. | - | | - | The maximum returned value is (ignoring exponents) | - | .ffffffff ffffffff | - | ------------------ = 1.ffffffff fffffffe | - | .80000000 00000000 | - | and the minimum is | - | .80000000 00000000 | - | ------------------ = .80000000 00000001 (rounded) | - | .ffffffff ffffffff | - | | - +---------------------------------------------------------------------------*/ - - -L_Full_Division: - /* Save extended dividend in local register */ - movl SIGL(%esi),%eax - movl %eax,FPU_accum_2 - movl SIGH(%esi),%eax - movl %eax,FPU_accum_3 - xorl %eax,%eax - movl %eax,FPU_accum_1 /* zero the extension */ - movl %eax,FPU_accum_0 /* zero the extension */ - - movl SIGL(%esi),%eax /* Get the current num */ - movl SIGH(%esi),%edx - -/*----------------------------------------------------------------------*/ -/* Initialization done. - Do the first 32 bits. */ - - movb $0,FPU_ovfl_flag - cmpl SIGH(%ebx),%edx /* Test for imminent overflow */ - jb LLess_than_1 - ja LGreater_than_1 - - cmpl SIGL(%ebx),%eax - jb LLess_than_1 - -LGreater_than_1: -/* The dividend is greater or equal, would cause overflow */ - setaeb FPU_ovfl_flag /* Keep a record */ - - subl SIGL(%ebx),%eax - sbbl SIGH(%ebx),%edx /* Prevent the overflow */ - movl %eax,FPU_accum_2 - movl %edx,FPU_accum_3 - -LLess_than_1: -/* At this point, we have a dividend < divisor, with a record of - adjustment in FPU_ovfl_flag */ - - /* We will divide by a number which is too large */ - movl SIGH(%ebx),%ecx - addl $1,%ecx - jnc LFirst_div_not_1 - - /* here we need to divide by 100000000h, - i.e., no division at all.. */ - mov %edx,%eax - jmp LFirst_div_done - -LFirst_div_not_1: - divl %ecx /* Divide the numerator by the augmented - denom ms dw */ - -LFirst_div_done: - movl %eax,FPU_result_2 /* Put the result in the answer */ - - mull SIGH(%ebx) /* mul by the ms dw of the denom */ - - subl %eax,FPU_accum_2 /* Subtract from the num local reg */ - sbbl %edx,FPU_accum_3 - - movl FPU_result_2,%eax /* Get the result back */ - mull SIGL(%ebx) /* now mul the ls dw of the denom */ - - subl %eax,FPU_accum_1 /* Subtract from the num local reg */ - sbbl %edx,FPU_accum_2 - sbbl $0,FPU_accum_3 - je LDo_2nd_32_bits /* Must check for non-zero result here */ - -#ifdef PARANOID - jb L_bugged_1 -#endif /* PARANOID */ - - /* need to subtract another once of the denom */ - incl FPU_result_2 /* Correct the answer */ - - movl SIGL(%ebx),%eax - movl SIGH(%ebx),%edx - subl %eax,FPU_accum_1 /* Subtract from the num local reg */ - sbbl %edx,FPU_accum_2 - -#ifdef PARANOID - sbbl $0,FPU_accum_3 - jne L_bugged_1 /* Must check for non-zero result here */ -#endif /* PARANOID */ - -/*----------------------------------------------------------------------*/ -/* Half of the main problem is done, there is just a reduced numerator - to handle now. - Work with the second 32 bits, FPU_accum_0 not used from now on */ -LDo_2nd_32_bits: - movl FPU_accum_2,%edx /* get the reduced num */ - movl FPU_accum_1,%eax - - /* need to check for possible subsequent overflow */ - cmpl SIGH(%ebx),%edx - jb LDo_2nd_div - ja LPrevent_2nd_overflow - - cmpl SIGL(%ebx),%eax - jb LDo_2nd_div - -LPrevent_2nd_overflow: -/* The numerator is greater or equal, would cause overflow */ - /* prevent overflow */ - subl SIGL(%ebx),%eax - sbbl SIGH(%ebx),%edx - movl %edx,FPU_accum_2 - movl %eax,FPU_accum_1 - - incl FPU_result_2 /* Reflect the subtraction in the answer */ - -#ifdef PARANOID - je L_bugged_2 /* Can't bump the result to 1.0 */ -#endif /* PARANOID */ - -LDo_2nd_div: - cmpl $0,%ecx /* augmented denom msw */ - jnz LSecond_div_not_1 - - /* %ecx == 0, we are dividing by 1.0 */ - mov %edx,%eax - jmp LSecond_div_done - -LSecond_div_not_1: - divl %ecx /* Divide the numerator by the denom ms dw */ - -LSecond_div_done: - movl %eax,FPU_result_1 /* Put the result in the answer */ - - mull SIGH(%ebx) /* mul by the ms dw of the denom */ - - subl %eax,FPU_accum_1 /* Subtract from the num local reg */ - sbbl %edx,FPU_accum_2 - -#ifdef PARANOID - jc L_bugged_2 -#endif /* PARANOID */ - - movl FPU_result_1,%eax /* Get the result back */ - mull SIGL(%ebx) /* now mul the ls dw of the denom */ - - subl %eax,FPU_accum_0 /* Subtract from the num local reg */ - sbbl %edx,FPU_accum_1 /* Subtract from the num local reg */ - sbbl $0,FPU_accum_2 - -#ifdef PARANOID - jc L_bugged_2 -#endif /* PARANOID */ - - jz LDo_3rd_32_bits - -#ifdef PARANOID - cmpl $1,FPU_accum_2 - jne L_bugged_2 -#endif /* PARANOID */ - - /* need to subtract another once of the denom */ - movl SIGL(%ebx),%eax - movl SIGH(%ebx),%edx - subl %eax,FPU_accum_0 /* Subtract from the num local reg */ - sbbl %edx,FPU_accum_1 - sbbl $0,FPU_accum_2 - -#ifdef PARANOID - jc L_bugged_2 - jne L_bugged_2 -#endif /* PARANOID */ - - addl $1,FPU_result_1 /* Correct the answer */ - adcl $0,FPU_result_2 - -#ifdef PARANOID - jc L_bugged_2 /* Must check for non-zero result here */ -#endif /* PARANOID */ - -/*----------------------------------------------------------------------*/ -/* The division is essentially finished here, we just need to perform - tidying operations. - Deal with the 3rd 32 bits */ -LDo_3rd_32_bits: - movl FPU_accum_1,%edx /* get the reduced num */ - movl FPU_accum_0,%eax - - /* need to check for possible subsequent overflow */ - cmpl SIGH(%ebx),%edx /* denom */ - jb LRound_prep - ja LPrevent_3rd_overflow - - cmpl SIGL(%ebx),%eax /* denom */ - jb LRound_prep - -LPrevent_3rd_overflow: - /* prevent overflow */ - subl SIGL(%ebx),%eax - sbbl SIGH(%ebx),%edx - movl %edx,FPU_accum_1 - movl %eax,FPU_accum_0 - - addl $1,FPU_result_1 /* Reflect the subtraction in the answer */ - adcl $0,FPU_result_2 - jne LRound_prep - jnc LRound_prep - - /* This is a tricky spot, there is an overflow of the answer */ - movb $255,FPU_ovfl_flag /* Overflow -> 1.000 */ - -LRound_prep: -/* - * Prepare for rounding. - * To test for rounding, we just need to compare 2*accum with the - * denom. - */ - movl FPU_accum_0,%ecx - movl FPU_accum_1,%edx - movl %ecx,%eax - orl %edx,%eax - jz LRound_ovfl /* The accumulator contains zero. */ - - /* Multiply by 2 */ - clc - rcll $1,%ecx - rcll $1,%edx - jc LRound_large /* No need to compare, denom smaller */ - - subl SIGL(%ebx),%ecx - sbbl SIGH(%ebx),%edx - jnc LRound_not_small - - movl $0x70000000,%eax /* Denom was larger */ - jmp LRound_ovfl - -LRound_not_small: - jnz LRound_large - - movl $0x80000000,%eax /* Remainder was exactly 1/2 denom */ - jmp LRound_ovfl - -LRound_large: - movl $0xff000000,%eax /* Denom was smaller */ - -LRound_ovfl: -/* We are now ready to deal with rounding, but first we must get - the bits properly aligned */ - testb $255,FPU_ovfl_flag /* was the num > denom ? */ - je LRound_precision - - incw EXP(%edi) - - /* shift the mantissa right one bit */ - stc /* Will set the ms bit */ - rcrl FPU_result_2 - rcrl FPU_result_1 - rcrl %eax - -/* Round the result as required */ -LRound_precision: - decw EXP(%edi) /* binary point between 1st & 2nd bits */ - - movl %eax,%edx - movl FPU_result_1,%ebx - movl FPU_result_2,%eax - jmp fpu_reg_round - - -#ifdef PARANOID -/* The logic is wrong if we got here */ -L_bugged: - pushl EX_INTERNAL|0x202 - call EXCEPTION - pop %ebx - jmp L_exit - -L_bugged_1: - pushl EX_INTERNAL|0x203 - call EXCEPTION - pop %ebx - jmp L_exit - -L_bugged_2: - pushl EX_INTERNAL|0x204 - call EXCEPTION - pop %ebx - jmp L_exit - -L_exit: - movl $-1,%eax - popl %ebx - popl %edi - popl %esi - - leave - ret -#endif /* PARANOID */ |
