fpudispatch.c

这个linux源代码是很全面的~基本完整了~使用c编译的~由于时间问题我没有亲自测试~但就算用来做参考资料也是非常好的

/*
 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
 *
 * Floating-point emulation code
 *  Copyright (C) 2001 Hewlett-Packard (Paul Bame) <[e-mail]>
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2, or (at your option)
 *    any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
/*
 * BEGIN_DESC
 *
 *  File:
 *	@(#)	pa/fp/fpudispatch.c		$Revision: 1.1 $
 *
 *  Purpose:
 *	<<please update with a synopsis of the functionality provided by this file>>
 *
 *  External Interfaces:
 *	<<the following list was autogenerated, please review>>
 *	emfpudispatch(ir, dummy1, dummy2, fpregs)
 *	fpudispatch(ir, excp_code, holder, fpregs)
 *
 *  Internal Interfaces:
 *	<<the following list was autogenerated, please review>>
 *	static u_int decode_06(u_int, u_int *)
 *	static u_int decode_0c(u_int, u_int, u_int, u_int *)
 *	static u_int decode_0e(u_int, u_int, u_int, u_int *)
 *	static u_int decode_26(u_int, u_int *)
 *	static u_int decode_2e(u_int, u_int *)
 *	static void update_status_cbit(u_int *, u_int, u_int, u_int)
 *
 *  Theory:
 *	<<please update with a overview of the operation of this file>>
 *
 * END_DESC
*/

#define FPUDEBUG 0

#include "float.h"
#include "types.h"
/* #include <sys/debug.h> */
/* #include <machine/sys/mdep_private.h> */

#define COPR_INST 0x30000000

/*
 * definition of extru macro.  If pos and len are constants, the compiler
 * will generate an extru instruction when optimized
 */
#define extru(r,pos,len)	(((r) >> (31-(pos))) & (( 1 << (len)) - 1))
/* definitions of bit field locations in the instruction */
#define fpmajorpos 5
#define fpr1pos	10
#define fpr2pos 15
#define fptpos	31
#define fpsubpos 18
#define fpclass1subpos 16
#define fpclasspos 22
#define fpfmtpos 20
#define fpdfpos 18
#define fpnulpos 26
/*
 * the following are the extra bits for the 0E major op
 */
#define fpxr1pos 24
#define fpxr2pos 19
#define fpxtpos 25
#define fpxpos 23
#define fp0efmtpos 20
/*
 * the following are for the multi-ops
 */
#define fprm1pos 10
#define fprm2pos 15
#define fptmpos 31
#define fprapos 25
#define fptapos 20
#define fpmultifmt 26
/*
 * the following are for the fused FP instructions
 */
     /* fprm1pos 10 */
     /* fprm2pos 15 */
#define fpraupos 18
#define fpxrm2pos 19
     /* fpfmtpos 20 */
#define fpralpos 23
#define fpxrm1pos 24
     /* fpxtpos 25 */
#define fpfusedsubop 26
     /* fptpos	31 */

/*
 * offset to constant zero in the FP emulation registers
 */
#define fpzeroreg (32*sizeof(double)/sizeof(u_int))

/*
 * extract the major opcode from the instruction
 */
#define get_major(op) extru(op,fpmajorpos,6)
/*
 * extract the two bit class field from the FP instruction. The class is at bit
 * positions 21-22
 */
#define get_class(op) extru(op,fpclasspos,2)
/*
 * extract the 3 bit subop field.  For all but class 1 instructions, it is
 * located at bit positions 16-18
 */
#define get_subop(op) extru(op,fpsubpos,3)
/*
 * extract the 2 or 3 bit subop field from class 1 instructions.  It is located
 * at bit positions 15-16 (PA1.1) or 14-16 (PA2.0)
 */
#define get_subop1_PA1_1(op) extru(op,fpclass1subpos,2)	/* PA89 (1.1) fmt */
#define get_subop1_PA2_0(op) extru(op,fpclass1subpos,3)	/* PA 2.0 fmt */

/* definitions of unimplemented exceptions */
#define MAJOR_0C_EXCP	0x09
#define MAJOR_0E_EXCP	0x0b
#define MAJOR_06_EXCP	0x03
#define MAJOR_26_EXCP	0x23
#define MAJOR_2E_EXCP	0x2b
#define PA83_UNIMP_EXCP	0x01

/*
 * Special Defines for TIMEX specific code
 */

#define FPU_TYPE_FLAG_POS (EM_FPU_TYPE_OFFSET>>2)
#define TIMEX_ROLEX_FPU_MASK (TIMEX_EXTEN_FLAG|ROLEX_EXTEN_FLAG)

/*
 * Static function definitions
 */
#define _PROTOTYPES
#if defined(_PROTOTYPES) || defined(_lint)
static u_int decode_0c(u_int, u_int, u_int, u_int *);
static u_int decode_0e(u_int, u_int, u_int, u_int *);
static u_int decode_06(u_int, u_int *);
static u_int decode_26(u_int, u_int *);
static u_int decode_2e(u_int, u_int *);
static void update_status_cbit(u_int *, u_int, u_int, u_int);
#else /* !_PROTOTYPES&&!_lint */
static u_int decode_0c();
static u_int decode_0e();
static u_int decode_06();
static u_int decode_26();
static u_int decode_2e();
static void update_status_cbit();
#endif /* _PROTOTYPES&&!_lint */

#define VASSERT(x)

/*
 * this routine will decode the excepting floating point instruction and
 * call the approiate emulation routine.
 * It is called by decode_fpu with the following parameters:
 * fpudispatch(current_ir, unimplemented_code, 0, &Fpu_register)
 * where current_ir is the instruction to be emulated,
 * unimplemented_code is the exception_code that the hardware generated
 * and &Fpu_register is the address of emulated FP reg 0.
 */
u_int
fpudispatch(u_int ir, u_int excp_code, u_int holder, u_int fpregs[])
{
	u_int class, subop;
	u_int fpu_type_flags;

	/* All FP emulation code assumes that ints are 4-bytes in length */
	VASSERT(sizeof(int) == 4);

	fpu_type_flags=fpregs[FPU_TYPE_FLAG_POS];  /* get fpu type flags */

	class = get_class(ir);
	if (class == 1) {
		if  (fpu_type_flags & PA2_0_FPU_FLAG)
			subop = get_subop1_PA2_0(ir);
		else
			subop = get_subop1_PA1_1(ir);
	}
	else
		subop = get_subop(ir);

	if (FPUDEBUG) printk("class %d subop %d\n", class, subop);

	switch (excp_code) {
		case MAJOR_0C_EXCP:
		case PA83_UNIMP_EXCP:
			return(decode_0c(ir,class,subop,fpregs));
		case MAJOR_0E_EXCP:
			return(decode_0e(ir,class,subop,fpregs));
		case MAJOR_06_EXCP:
			return(decode_06(ir,fpregs));
		case MAJOR_26_EXCP:
			return(decode_26(ir,fpregs));
		case MAJOR_2E_EXCP:
			return(decode_2e(ir,fpregs));
		default:
			/* "crashme Night Gallery painting nr 2. (asm_crash.s).
			 * This was fixed for multi-user kernels, but
			 * workstation kernels had a panic here.  This allowed
			 * any arbitrary user to panic the kernel by executing
			 * setting the FP exception registers to strange values
			 * and generating an emulation trap.  The emulation and
			 * exception code must never be able to panic the
			 * kernel.
			 */
			return(UNIMPLEMENTEDEXCEPTION);
	}
}

/*
 * this routine is called by $emulation_trap to emulate a coprocessor
 * instruction if one doesn't exist
 */
u_int
emfpudispatch(u_int ir, u_int dummy1, u_int dummy2, u_int fpregs[])
{
	u_int class, subop, major;
	u_int fpu_type_flags;

	/* All FP emulation code assumes that ints are 4-bytes in length */
	VASSERT(sizeof(int) == 4);

	fpu_type_flags=fpregs[FPU_TYPE_FLAG_POS];  /* get fpu type flags */

	major = get_major(ir);
	class = get_class(ir);
	if (class == 1) {
		if  (fpu_type_flags & PA2_0_FPU_FLAG)
			subop = get_subop1_PA2_0(ir);
		else
			subop = get_subop1_PA1_1(ir);
	}
	else
		subop = get_subop(ir);
	switch (major) {
		case 0x0C:
			return(decode_0c(ir,class,subop,fpregs));
		case 0x0E:
			return(decode_0e(ir,class,subop,fpregs));
		case 0x06:
			return(decode_06(ir,fpregs));
		case 0x26:
			return(decode_26(ir,fpregs));
		case 0x2E:
			return(decode_2e(ir,fpregs));
		default:
			return(PA83_UNIMP_EXCP);
	}
}
	

static u_int
decode_0c(u_int ir, u_int class, u_int subop, u_int fpregs[])
{
	u_int r1,r2,t;		/* operand register offsets */ 
	u_int fmt;		/* also sf for class 1 conversions */
	u_int  df;		/* for class 1 conversions */
	u_int *status;
	u_int retval, local_status;
	u_int fpu_type_flags;

	if (ir == COPR_INST) {
		fpregs[0] = EMULATION_VERSION << 11;
		return(NOEXCEPTION);
	}
	status = &fpregs[0];	/* fp status register */
	local_status = fpregs[0]; /* and local copy */
	r1 = extru(ir,fpr1pos,5) * sizeof(double)/sizeof(u_int);
	if (r1 == 0)		/* map fr0 source to constant zero */
		r1 = fpzeroreg;
	t = extru(ir,fptpos,5) * sizeof(double)/sizeof(u_int);
	if (t == 0 && class != 2)	/* don't allow fr0 as a dest */
		return(MAJOR_0C_EXCP);
	fmt = extru(ir,fpfmtpos,2);	/* get fmt completer */

	switch (class) {
	    case 0:
		switch (subop) {
			case 0:	/* COPR 0,0 emulated above*/
			case 1:
				return(MAJOR_0C_EXCP);
			case 2:	/* FCPY */
				switch (fmt) {
				    case 2: /* illegal */
					return(MAJOR_0C_EXCP);
				    case 3: /* quad */
					t &= ~3;  /* force to even reg #s */
					r1 &= ~3;
					fpregs[t+3] = fpregs[r1+3];
					fpregs[t+2] = fpregs[r1+2];
				    case 1: /* double */
					fpregs[t+1] = fpregs[r1+1];
				    case 0: /* single */
					fpregs[t] = fpregs[r1];
					return(NOEXCEPTION);
				}
			case 3: /* FABS */
				switch (fmt) {
				    case 2: /* illegal */
					return(MAJOR_0C_EXCP);
				    case 3: /* quad */
					t &= ~3;  /* force to even reg #s */
					r1 &= ~3;
					fpregs[t+3] = fpregs[r1+3];
					fpregs[t+2] = fpregs[r1+2];
				    case 1: /* double */
					fpregs[t+1] = fpregs[r1+1];
				    case 0: /* single */
					/* copy and clear sign bit */
					fpregs[t] = fpregs[r1] & 0x7fffffff;
					return(NOEXCEPTION);
				}
			case 6: /* FNEG */
				switch (fmt) {
				    case 2: /* illegal */
					return(MAJOR_0C_EXCP);
				    case 3: /* quad */
					t &= ~3;  /* force to even reg #s */
					r1 &= ~3;
					fpregs[t+3] = fpregs[r1+3];
					fpregs[t+2] = fpregs[r1+2];
				    case 1: /* double */
					fpregs[t+1] = fpregs[r1+1];
				    case 0: /* single */
					/* copy and invert sign bit */
					fpregs[t] = fpregs[r1] ^ 0x80000000;
					return(NOEXCEPTION);
				}
			case 7: /* FNEGABS */
				switch (fmt) {
				    case 2: /* illegal */
					return(MAJOR_0C_EXCP);
				    case 3: /* quad */
					t &= ~3;  /* force to even reg #s */
					r1 &= ~3;
					fpregs[t+3] = fpregs[r1+3];
					fpregs[t+2] = fpregs[r1+2];
				    case 1: /* double */
					fpregs[t+1] = fpregs[r1+1];
				    case 0: /* single */
					/* copy and set sign bit */
					fpregs[t] = fpregs[r1] | 0x80000000;
					return(NOEXCEPTION);
				}
			case 4: /* FSQRT */
				switch (fmt) {
				    case 0:
					return(sgl_fsqrt(&fpregs[r1],0,
						&fpregs[t],status));
				    case 1:
					return(dbl_fsqrt(&fpregs[r1],0,
						&fpregs[t],status));
				    case 2:
				    case 3: /* quad not implemented */
					return(MAJOR_0C_EXCP);
				}
			case 5: /* FRND */
				switch (fmt) {
				    case 0:
					return(sgl_frnd(&fpregs[r1],0,
						&fpregs[t],status));
				    case 1:
					return(dbl_frnd(&fpregs[r1],0,
						&fpregs[t],status));
				    case 2:
				    case 3: /* quad not implemented */
					return(MAJOR_0C_EXCP);
				}
		} /* end of switch (subop) */

	case 1: /* class 1 */
		df = extru(ir,fpdfpos,2); /* get dest format */
		if ((df & 2) || (fmt & 2)) {
			/*
			 * fmt's 2 and 3 are illegal of not implemented
			 * quad conversions
			 */
			return(MAJOR_0C_EXCP);
		}
		/*
		 * encode source and dest formats into 2 bits.
		 * high bit is source, low bit is dest.
		 * bit = 1 --> double precision
		 */
		fmt = (fmt << 1) | df;
		switch (subop) {
			case 0: /* FCNVFF */
				switch(fmt) {
				    case 0: /* sgl/sgl */
					return(MAJOR_0C_EXCP);
				    case 1: /* sgl/dbl */
					return(sgl_to_dbl_fcnvff(&fpregs[r1],0,
						&fpregs[t],status));
				    case 2: /* dbl/sgl */
					return(dbl_to_sgl_fcnvff(&fpregs[r1],0,
						&fpregs[t],status));
				    case 3: /* dbl/dbl */
					return(MAJOR_0C_EXCP);
				}
			case 1: /* FCNVXF */
				switch(fmt) {
				    case 0: /* sgl/sgl */
					return(sgl_to_sgl_fcnvxf(&fpregs[r1],0,
						&fpregs[t],status));
				    case 1: /* sgl/dbl */
					return(sgl_to_dbl_fcnvxf(&fpregs[r1],0,
						&fpregs[t],status));
				    case 2: /* dbl/sgl */
					return(dbl_to_sgl_fcnvxf(&fpregs[r1],0,
						&fpregs[t],status));
				    case 3: /* dbl/dbl */
					return(dbl_to_dbl_fcnvxf(&fpregs[r1],0,
						&fpregs[t],status));
				}
			case 2: /* FCNVFX */
				switch(fmt) {
				    case 0: /* sgl/sgl */
					return(sgl_to_sgl_fcnvfx(&fpregs[r1],0,
						&fpregs[t],status));
				    case 1: /* sgl/dbl */
					return(sgl_to_dbl_fcnvfx(&fpregs[r1],0,
						&fpregs[t],status));
				    case 2: /* dbl/sgl */
					return(dbl_to_sgl_fcnvfx(&fpregs[r1],0,
						&fpregs[t],status));
				    case 3: /* dbl/dbl */
					return(dbl_to_dbl_fcnvfx(&fpregs[r1],0,
						&fpregs[t],status));
				}
			case 3: /* FCNVFXT */
				switch(fmt) {
				    case 0: /* sgl/sgl */
					return(sgl_to_sgl_fcnvfxt(&fpregs[r1],0,
						&fpregs[t],status));
				    case 1: /* sgl/dbl */
					return(sgl_to_dbl_fcnvfxt(&fpregs[r1],0,
						&fpregs[t],status));
				    case 2: /* dbl/sgl */
					return(dbl_to_sgl_fcnvfxt(&fpregs[r1],0,
						&fpregs[t],status));
				    case 3: /* dbl/dbl */
					return(dbl_to_dbl_fcnvfxt(&fpregs[r1],0,
						&fpregs[t],status));
				}
			case 5: /* FCNVUF (PA2.0 only) */
				switch(fmt) {
				    case 0: /* sgl/sgl */
					return(sgl_to_sgl_fcnvuf(&fpregs[r1],0,
						&fpregs[t],status));
				    case 1: /* sgl/dbl */
					return(sgl_to_dbl_fcnvuf(&fpregs[r1],0,
						&fpregs[t],status));
				    case 2: /* dbl/sgl */
					return(dbl_to_sgl_fcnvuf(&fpregs[r1],0,
						&fpregs[t],status));
				    case 3: /* dbl/dbl */
					return(dbl_to_dbl_fcnvuf(&fpregs[r1],0,
						&fpregs[t],status));
				}