3 NetWinder Floating Point Emulator
4 (c) Rebel.com, 1998-1999
5 (c) Philip Blundell, 1998-1999
7 Direct questions, comments to Scott Bambrough <scottb@netwinder.org>
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 2 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
26 #include <linux/module.h>
27 #include <linux/version.h>
28 #include <linux/config.h>
31 #include <linux/types.h>
32 #include <linux/kernel.h>
33 #include <linux/signal.h>
34 #include <linux/sched.h>
35 #include <linux/init.h>
38 #include "softfloat.h"
43 /* kernel symbols required for signal handling */
44 typedef struct task_struct *PTASK;
46 #ifdef CONFIG_FPE_NWFPE_XP
47 #define NWFPE_BITS "extended"
49 #define NWFPE_BITS "double"
53 void fp_send_sig(unsigned long sig, PTASK p, int priv);
54 #if LINUX_VERSION_CODE > 0x20115
55 MODULE_AUTHOR("Scott Bambrough <scottb@rebel.com>");
56 MODULE_DESCRIPTION("NWFPE floating point emulator (" NWFPE_BITS " precision)");
60 #define fp_send_sig send_sig
61 #define kern_fp_enter fp_enter
63 extern char fpe_type[];
66 /* kernel function prototypes required */
69 /* external declarations for saved kernel symbols */
70 extern void (*kern_fp_enter)(void);
72 /* Original value of fp_enter from kernel before patched by fpe_init. */
73 static void (*orig_fp_enter)(void);
75 /* forward declarations */
76 extern void nwfpe_enter(void);
80 * Return 0 if we can be unloaded. This can only happen if
81 * kern_fp_enter is still pointing at nwfpe_enter
83 static int fpe_unload(void)
85 return (kern_fp_enter == nwfpe_enter) ? 0 : 1;
89 static int __init fpe_init(void)
91 if (sizeof(FPA11) > sizeof(union fp_state)) {
92 printk(KERN_ERR "nwfpe: bad structure size\n");
96 if (sizeof(FPREG) != 12) {
97 printk(KERN_ERR "nwfpe: bad register size\n");
101 if (!mod_member_present(&__this_module, can_unload))
103 __this_module.can_unload = fpe_unload;
105 if (fpe_type[0] && strcmp(fpe_type, "nwfpe"))
109 /* Display title, version and copyright information. */
110 printk(KERN_WARNING "NetWinder Floating Point Emulator V0.97 ("
111 NWFPE_BITS " precision)\n");
113 /* Save pointer to the old FP handler and then patch ourselves in */
114 orig_fp_enter = kern_fp_enter;
115 kern_fp_enter = nwfpe_enter;
120 static void __exit fpe_exit(void)
122 /* Restore the values we saved earlier. */
123 kern_fp_enter = orig_fp_enter;
127 ScottB: November 4, 1998
129 Moved this function out of softfloat-specialize into fpmodule.c.
130 This effectively isolates all the changes required for integrating with the
131 Linux kernel into fpmodule.c. Porting to NetBSD should only require modifying
132 fpmodule.c to integrate with the NetBSD kernel (I hope!).
134 [1/1/99: Not quite true any more unfortunately. There is Linux-specific
135 code to access data in user space in some other source files at the
136 moment (grep for get_user / put_user calls). --philb]
138 float_exception_flags is a global variable in SoftFloat.
140 This function is called by the SoftFloat routines to raise a floating
141 point exception. We check the trap enable byte in the FPSR, and raise
142 a SIGFPE exception if necessary. If not the relevant bits in the
143 cumulative exceptions flag byte are set and we return.
146 void float_raise(signed char flags)
148 register unsigned int fpsr, cumulativeTraps;
150 #ifdef CONFIG_DEBUG_USER
152 "NWFPE: %s[%d] takes exception %08x at %p from %08x\n",
153 current->comm, current->pid, flags,
154 __builtin_return_address(0), GET_USERREG()[15]);
157 /* Keep SoftFloat exception flags up to date. */
158 float_exception_flags |= flags;
160 /* Read fpsr and initialize the cumulativeTraps. */
164 /* For each type of exception, the cumulative trap exception bit is only
165 set if the corresponding trap enable bit is not set. */
166 if ((!(fpsr & BIT_IXE)) && (flags & BIT_IXC))
167 cumulativeTraps |= BIT_IXC;
168 if ((!(fpsr & BIT_UFE)) && (flags & BIT_UFC))
169 cumulativeTraps |= BIT_UFC;
170 if ((!(fpsr & BIT_OFE)) && (flags & BIT_OFC))
171 cumulativeTraps |= BIT_OFC;
172 if ((!(fpsr & BIT_DZE)) && (flags & BIT_DZC))
173 cumulativeTraps |= BIT_DZC;
174 if ((!(fpsr & BIT_IOE)) && (flags & BIT_IOC))
175 cumulativeTraps |= BIT_IOC;
177 /* Set the cumulative exceptions flags. */
179 writeFPSR(fpsr | cumulativeTraps);
181 /* Raise an exception if necessary. */
182 if (fpsr & (flags << 16))
183 fp_send_sig(SIGFPE, current, 1);
186 module_init(fpe_init);
187 module_exit(fpe_exit);