From 7e0f021a9aec35fd8e6725e87e3313b101d26f5e Mon Sep 17 00:00:00 2001
From: Tobias Klauser <tklauser@distanz.ch>
Date: Sun, 27 Jan 2008 11:37:44 +0100
Subject: Initial import (2.0.2-6)

---
 reference/C/CONTRIB/SNIP/8087_sav.asm | 73 +++++++++++++++++++++++++++++++++++
 1 file changed, 73 insertions(+)
 create mode 100755 reference/C/CONTRIB/SNIP/8087_sav.asm

(limited to 'reference/C/CONTRIB/SNIP/8087_sav.asm')

diff --git a/reference/C/CONTRIB/SNIP/8087_sav.asm b/reference/C/CONTRIB/SNIP/8087_sav.asm
new file mode 100755
index 0000000..603303f
--- /dev/null
+++ b/reference/C/CONTRIB/SNIP/8087_sav.asm
@@ -0,0 +1,73 @@
+; By: Jeffrey Nonken 
+
+        page    60,132
+        .286
+
+_text   segment byte public 'code'
+_text   ends
+_data   segment  word public 'data'
+_data   ends
+const   segment  word public 'const'
+const   ends
+_bss    segment  word public 'bss'
+_bss    ends
+dgroup  group   const,  _bss,   _data
+        assume  cs: _text, ds: nothing
+
+_data   segment  word public 'data'
+        even
+env_8087        dw      47 dup (?)
+norm_8087       dw      177fh
+_data   ends
+
+_text   segment byte public 'code'
+;
+; This code saves the 80x87 enviroment and sets up our own. First, this
+; assumes you are running an 80287; the 8087 may require more FWAIT
+; operations. Second, I decided that I didn't want to handle exceptions, so
+; I simply disabled them. That means that if the 80x87 gets an invalid result
+; (such as divide-by-zero) the 80x87 will continue to run and will produce
+; invalid results until the end of your current calculation. Anything that
+; depends on the results will, of course, also be invalid. If you want
+; exceptions to be handled, get documentation for the 80x87 and you will
+; see how to set norm_8087 (above) to suit your needs. If you are running
+; an 8087 and don't know where to put FWAIT instructions, you can always
+; add one after each floating-point instruction. NOTE: FWAIT is synonymous
+; to WAIT. They are the same instruction.
+;
+; This was written for TURBO C and will also work with MSC. It should work
+; with any programming language with no more than minor changes in the
+; label names or the interface. Consult your compiler manual for more detail.
+; I wrote this so it would work with either the tiny or small models.
+; Actually, it will probably work with any of the models. You should be
+; able to assemble this with MASM and link it right in.
+;
+; extern save_8087();
+; extern restore_8087();
+;
+        public  _save_8087
+_save_8087      proc    near
+        cli                             ; no interruptions!
+        lea     bx,dgroup:env_8087      ; point to save area
+        fwait                           ; make sure processor is ready
+        fnsave  [bx]                    ; save the 8087 environment
+        lea     bx,dgroup:norm_8087     ; point to our new 8087 setup
+        mov     ax,[bx]                 ; get it
+        fldcw   [bx]                    ; set it
+        fwait
+        sti                             ; restore interrupts
+        ret
+_save_8087      endp
+
+        public  _restore_8087
+_restore_8087   proc    near
+        cli                             ; no interruptions!
+        lea     bx,dgroup:env_8087      ; point to saved 8087 stuff
+        frstor  [bx]                    ; restore the 8087 environment
+        sti                             ; restore interrupts
+        ret
+_restore_8087   endp
+
+_text   ends
+
+        end
-- 
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