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Diffstat (limited to 'arch/metag/lib/divsi3.S')
| -rw-r--r-- | arch/metag/lib/divsi3.S | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/arch/metag/lib/divsi3.S b/arch/metag/lib/divsi3.S new file mode 100644 index 00000000000..7c8a8ae9a0a --- /dev/null +++ b/arch/metag/lib/divsi3.S @@ -0,0 +1,100 @@ +! Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007 +! Imagination Technologies Ltd +! +! Integer divide routines. +! + + .text + .global ___udivsi3 + .type ___udivsi3,function + .align 2 +___udivsi3: +!! +!! Since core is signed divide case, just set control variable +!! + MOV D1Re0,D0Ar2 ! Au already in A1Ar1, Bu -> D1Re0 + MOV D0Re0,#0 ! Result is 0 + MOV D0Ar4,#0 ! Return positive result + B $LIDMCUStart + .size ___udivsi3,.-___udivsi3 + +!! +!! 32-bit division signed i/p - passed signed 32-bit numbers +!! + .global ___divsi3 + .type ___divsi3,function + .align 2 +___divsi3: +!! +!! A already in D1Ar1, B already in D0Ar2 -> make B abs(B) +!! + MOV D1Re0,D0Ar2 ! A already in A1Ar1, B -> D1Re0 + MOV D0Re0,#0 ! Result is 0 + XOR D0Ar4,D1Ar1,D1Re0 ! D0Ar4 -ive if result is -ive + ABS D1Ar1,D1Ar1 ! abs(A) -> Au + ABS D1Re0,D1Re0 ! abs(B) -> Bu +$LIDMCUStart: + CMP D1Ar1,D1Re0 ! Is ( Au > Bu )? + LSR D1Ar3,D1Ar1,#2 ! Calculate (Au & (~3)) >> 2 + CMPHI D1Re0,D1Ar3 ! OR ( (Au & (~3)) <= (Bu << 2) )? + LSLSHI D1Ar3,D1Re0,#1 ! Buq = Bu << 1 + BLS $LIDMCUSetup ! Yes: Do normal divide +!! +!! Quick divide setup can assume that CurBit only needs to start at 2 +!! +$LIDMCQuick: + CMP D1Ar1,D1Ar3 ! ( A >= Buq )? + ADDCC D0Re0,D0Re0,#2 ! If yes result += 2 + SUBCC D1Ar1,D1Ar1,D1Ar3 ! and A -= Buq + CMP D1Ar1,D1Re0 ! ( A >= Bu )? + ADDCC D0Re0,D0Re0,#1 ! If yes result += 1 + SUBCC D1Ar1,D1Ar1,D1Re0 ! and A -= Bu + ORS D0Ar4,D0Ar4,D0Ar4 ! Return neg result? + NEG D0Ar2,D0Re0 ! Calulate neg result + MOVMI D0Re0,D0Ar2 ! Yes: Take neg result +$LIDMCRet: + MOV PC,D1RtP +!! +!! Setup for general unsigned divide code +!! +!! D0Re0 is used to form the result, already set to Zero +!! D1Re0 is the input Bu value, this gets trashed +!! D0Ar6 is curbit which is set to 1 at the start and shifted up +!! D0Ar4 is negative if we should return a negative result +!! D1Ar1 is the input Au value, eventually this holds the remainder +!! +$LIDMCUSetup: + CMP D1Ar1,D1Re0 ! Is ( Au < Bu )? + MOV D0Ar6,#1 ! Set curbit to 1 + BCS $LIDMCRet ! Yes: Return 0 remainder Au +!! +!! Calculate alignment using FFB instruction +!! + FFB D1Ar5,D1Ar1 ! Find first bit of Au + ANDN D1Ar5,D1Ar5,#31 ! Handle exceptional case. + ORN D1Ar5,D1Ar5,#31 ! if N bit set, set to 31 + FFB D1Ar3,D1Re0 ! Find first bit of Bu + ANDN D1Ar3,D1Ar3,#31 ! Handle exceptional case. + ORN D1Ar3,D1Ar3,#31 ! if N bit set, set to 31 + SUBS D1Ar3,D1Ar5,D1Ar3 ! calculate diff, ffbA - ffbB + MOV D0Ar2,D1Ar3 ! copy into bank 0 + LSLGT D1Re0,D1Re0,D1Ar3 ! ( > 0) ? left shift B + LSLGT D0Ar6,D0Ar6,D0Ar2 ! ( > 0) ? left shift curbit +!! +!! Now we start the divide proper, logic is +!! +!! if ( A >= B ) add curbit to result and subtract B from A +!! shift curbit and B down by 1 in either case +!! +$LIDMCLoop: + CMP D1Ar1, D1Re0 ! ( A >= B )? + ADDCC D0Re0, D0Re0, D0Ar6 ! If yes result += curbit + SUBCC D1Ar1, D1Ar1, D1Re0 ! and A -= B + LSRS D0Ar6, D0Ar6, #1 ! Shift down curbit, is it zero? + LSR D1Re0, D1Re0, #1 ! Shift down B + BNZ $LIDMCLoop ! Was single bit in curbit lost? + ORS D0Ar4,D0Ar4,D0Ar4 ! Return neg result? + NEG D0Ar2,D0Re0 ! Calulate neg result + MOVMI D0Re0,D0Ar2 ! Yes: Take neg result + MOV PC,D1RtP + .size ___divsi3,.-___divsi3 |