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Annotation of 43BSDTahoe/new/apl/apl.vax/src/ax.pdp.s, revision 1.1.1.1

1.1       root        1: /
                      2: /      APL assembly-language assist for floating-point
                      3: /
                      4: 
                      5: .globl _fppinit, _error
                      6: 
                      7: SIGFPE = 8.                    / signal # for flt-point exception
                      8: rtt = 6                                / opcode for RTT instruction
                      9: stst = 170300^tst              / "stst" opcode
                     10: bhs = bcc
                     11: 
                     12: /
                     13: / Enable FPP traps and route floating-point execeptions
                     14: / to special handler.
                     15: /
                     16: 
                     17: _fppinit:
                     18:        mov     r5,-(sp)
                     19:        mov     sp,r5
                     20:        sys     signal; SIGFPE; fpetrap
                     21:        stfps   r0
                     22:        bis     $7400,r0
                     23:        ldfps   r0
                     24:        mov     (sp)+,r5
                     25:        rts     pc
                     26: 
                     27: 
                     28: /
                     29: /      Exception trap handler
                     30: /
                     31: / Attempt to figure out the reason for the floating-point
                     32: / exception by immediately dumping the error register.
                     33: / If another process generates a floating-point exception
                     34: / before this service routine is called, the error register
                     35: / will be meaningless.  We just take our lumps in that case.
                     36: /
                     37: 
                     38: fpetrap:
                     39:        stst    fpstatus        / note: static allocation
                     40:        mov     r5,-(sp)
                     41:        mov     sp,r5
                     42:        mov     r1,-(sp)
                     43:        mov     r0,-(sp)
                     44:        sys     signal; SIGFPE; fpetrap
                     45:        mov     mesg,-(sp)      / default message
                     46:        mov     fpstatus,r0
                     47:        cmp     r0,$nmesg
                     48:        bhs     1f
                     49:        add     $mesg,r0        / pointer to specific message
                     50:        mov     (r0),(sp)
                     51: 1:
                     52:        jsr     pc, _error      / print error and APL traceback
                     53:        tst     (sp)+           / "can't" ever execute this code
                     54:        mov     (sp)+,r0
                     55:        mov     (sp)+,r1
                     56:        mov     (sp)+,r5
                     57:        rtt
                     58: 
                     59: .data
                     60: 
                     61: mesg:  mesg0
                     62:        mesg2
                     63:        mesg4
                     64:        mesg6
                     65:        mesg8
                     66:        mesg10
                     67:        mesg12
                     68:        mesg14
                     69: nmesg = . - mesg
                     70: 
                     71: mesg0: <floating exception\0>
                     72: mesg2: <floating opcode error\0>
                     73: mesg4: <floating divide by zero\0>
                     74: mesg6: <floating-to-integer conversion error\0>
                     75: mesg8: <floating overflow\0>
                     76: mesg10:        <floating underflow\0>
                     77: mesg12:        <undefined floating-point variable\0>
                     78: mesg14:        <floating-point maintenance trap\0>
                     79: .even
                     80: 
                     81: .bss
                     82: 
                     83: fpstatus: .=.+4

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