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Diffstat (limited to 'static/v10/man3/fptrap.3')
| -rw-r--r-- | static/v10/man3/fptrap.3 | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/static/v10/man3/fptrap.3 b/static/v10/man3/fptrap.3 new file mode 100644 index 00000000..489015c3 --- /dev/null +++ b/static/v10/man3/fptrap.3 @@ -0,0 +1,94 @@ +.pa 1 +.he '3/15/72''FPTRAP (III)' +.ti 0 +NAME fptrap -- PDP-11/45 floating point simulator +.sp +.ti 0 +.nf +SYNOPSIS .globl fptrap +.br +sys ilgins; fptrap +.fi +.sp +.ti 0 +DESCRIPTION fptrap______ +is a package which picks up instructions which are illegal +for the PDP-11/20, and if they correspond to 11/45 floating +point instructions, simulates their operation. +The following instructions are supported: + + cfcc + setf + seti + setd + setl +. ldfps src (not in assembler) +. stfps dst (not in assembler) + clrf fdst + tstf fsrc + absf fdst + negf fdst + mulf fsrc,fr + modf fsrc,fr + addf fsrc,fr + movf fsrc,fr (=ldf) + movf fr,fdst (=stf) + subf fsrc,fr + cmpf fsrc,fr + divf fsrc,fr +.nf +. movei fr,dst (=stexp) (not in assembler) +. movie src,fr (=ldexp) (not in assembler) + movfi fr,dst (=stcfi) + movif src,fr (=ldcif) + movfo fr,fdst (=stcxy) + movof fsrc,fr (=ldcyx) +.fi + +Here src___ and dst___ stand for source and destination, fsrc____ +and fdst____ for floating source and destination, and fr__ for +floating register. +Notice that the names of several of the opcodes have changed. +The only strange instruction +is movf____, which turns into stf___ if its source +operand is a floating register, and into ldf___ if not. +.sp +The simulator sets the floating condition codes +on both ldf___ and stf___. +The 11/45 hardware does not set +the fcc on stf. + +Short and long format for both floating point numbers +and integers is supported. Truncation mode is always in effect. +Traps for overflow and other arithmetic errors are not supported. +Illegal instructions or addresses cause a simulated trap +so that a core image is produced. + +The condition code bits are maintained correctly. + +For floating-point source operands, immediate mode ((pc)+) is +not supported, since the PDP-11/45 +handbook is not clear on what to do about it. + +After an arithmetic error the result is generally +meaningless. + +The arithmetic is always done in double-precision, so exact +but unrounded results are to be expected in single-precision +mode. Double precision results are probably less correct +than the hardware will be. + +The lower parts of the floating registers become meaningless +during single-precision operations. +.sp +.ti 0 +FILES kept in /usr/lib/liba.a +.sp +.ti 0 +SEE ALSO PDP-11/45 handbook, ilgins(II) +.sp +.ti 0 +DIAGNOSTICS trap, c-bit, v-bit +.sp +.ti 0 +BUGS see above |