+++ /dev/null
-/*
- * udivdi3.S - unsigned long long division
- *
- * Copyright 2003-2007 Analog Devices Inc.
- * Enter bugs at http://blackfin.uclinux.org/
- *
- * Licensed under the GPLv2 or later.
- */
-
-#include <linux/linkage.h>
-
-#define CARRY AC0
-
-#ifdef CONFIG_ARITHMETIC_OPS_L1
-.section .l1.text
-#else
-.text
-#endif
-
-
-ENTRY(___udivdi3)
- R3 = [SP + 12];
- [--SP] = (R7:4, P5:3);
-
- /* Attempt to use divide primitive first; these will handle
- ** most cases, and they're quick - avoids stalls incurred by
- ** testing for identities.
- */
-
- R4 = R2 | R3;
- CC = R4 == 0;
- IF CC JUMP .LDIV_BY_ZERO;
-
- R4.H = 0x8000;
- R4 >>>= 16; // R4 now 0xFFFF8000
- R5 = R0 | R2; // If either dividend or
- R4 = R5 & R4; // divisor have bits in
- CC = R4; // top half or low half's sign
- IF CC JUMP .LIDENTS; // bit, skip builtins.
- R4 = R1 | R3; // Also check top halves
- CC = R4;
- IF CC JUMP .LIDENTS;
-
- /* Can use the builtins. */
-
- AQ = CC; // Clear AQ (CC==0)
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- DIVQ(R0, R2);
- R0 = R0.L (Z);
- R1 = 0;
- (R7:4, P5:3) = [SP++];
- RTS;
-
-.LIDENTS:
- /* Test for common identities. Value to be returned is
- ** placed in R6,R7.
- */
- // Check for 0/y, return 0
- R4 = R0 | R1;
- CC = R4 == 0;
- IF CC JUMP .LRETURN_R0;
-
- // Check for x/x, return 1
- R6 = R0 - R2; // If x == y, then both R6 and R7 will be zero
- R7 = R1 - R3;
- R4 = R6 | R7; // making R4 zero.
- R6 += 1; // which would now make R6:R7==1.
- CC = R4 == 0;
- IF CC JUMP .LRETURN_IDENT;
-
- // Check for x/1, return x
- R6 = R0;
- R7 = R1;
- CC = R3 == 0;
- IF !CC JUMP .Lnexttest;
- CC = R2 == 1;
- IF CC JUMP .LRETURN_IDENT;
-
-.Lnexttest:
- R4.L = ONES R2; // check for div by power of two which
- R5.L = ONES R3; // can be done using a shift
- R6 = PACK (R5.L, R4.L);
- CC = R6 == 1;
- IF CC JUMP .Lpower_of_two_upper_zero;
- R6 = PACK (R4.L, R5.L);
- CC = R6 == 1;
- IF CC JUMP .Lpower_of_two_lower_zero;
-
- // Check for x < y, return 0
- R6 = 0;
- R7 = R6;
- CC = R1 < R3 (IU);
- IF CC JUMP .LRETURN_IDENT;
- CC = R1 == R3;
- IF !CC JUMP .Lno_idents;
- CC = R0 < R2 (IU);
- IF CC JUMP .LRETURN_IDENT;
-
-.Lno_idents: // Idents don't match. Go for the full operation
-
-
- // If X, or X and Y have high bit set, it'll affect the
- // results, so shift right one to stop this. Note: we've already
- // checked that X >= Y, so Y's msb won't be set unless X's
- // is.
-
- R4 = 0;
- CC = R1 < 0;
- IF !CC JUMP .Lx_msb_clear;
- CC = !CC; // 1 -> 0;
- R1 = ROT R1 BY -1; // Shift X >> 1
- R0 = ROT R0 BY -1; // lsb -> CC
- BITSET(R4,31); // to record only x msb was set
- CC = R3 < 0;
- IF !CC JUMP .Ly_msb_clear;
- CC = !CC;
- R3 = ROT R3 BY -1; // Shift Y >> 1
- R2 = ROT R2 BY -1;
- BITCLR(R4,31); // clear bit to record only x msb was set
-
-.Ly_msb_clear:
-.Lx_msb_clear:
- // Bit 31 in R4 indicates X msb set, but Y msb wasn't, and no bits
- // were lost, so we should shift result left by one.
-
- [--SP] = R4; // save for later
-
- // In the loop that follows, each iteration we add
- // either Y' or -Y' to the Remainder. We compute the
- // negated Y', and store, for convenience. Y' goes
- // into P0:P1, while -Y' goes into P2:P3.
-
- P0 = R2;
- P1 = R3;
- R2 = -R2;
- CC = CARRY;
- CC = !CC;
- R4 = CC;
- R3 = -R3;
- R3 = R3 - R4;
-
- R6 = 0; // remainder = 0
- R7 = R6;
-
- [--SP] = R2; P2 = SP;
- [--SP] = R3; P3 = SP;
- [--SP] = R6; P5 = SP; // AQ = 0
- [--SP] = P1;
-
- /* In the loop that follows, we use the following
- ** register assignments:
- ** R0,R1 X, workspace
- ** R2,R3 Y, workspace
- ** R4,R5 partial Div
- ** R6,R7 partial remainder
- ** P5 AQ
- ** The remainder and div form a 128-bit number, with
- ** the remainder in the high 64-bits.
- */
- R4 = R0; // Div = X'
- R5 = R1;
- R3 = 0;
-
- P4 = 64; // Iterate once per bit
- LSETUP(.LULST,.LULEND) LC0 = P4;
-.LULST:
- /* Shift Div and remainder up by one. The bit shifted
- ** out of the top of the quotient is shifted into the bottom
- ** of the remainder.
- */
- CC = R3;
- R4 = ROT R4 BY 1;
- R5 = ROT R5 BY 1 || // low q to high q
- R2 = [P5]; // load saved AQ
- R6 = ROT R6 BY 1 || // high q to low r
- R0 = [P2]; // load -Y'
- R7 = ROT R7 BY 1 || // low r to high r
- R1 = [P3];
-
- // Assume add -Y'
- CC = R2 < 0; // But if AQ is set...
- IF CC R0 = P0; // then add Y' instead
- IF CC R1 = P1;
-
- R6 = R6 + R0; // Rem += (Y' or -Y')
- CC = CARRY;
- R0 = CC;
- R7 = R7 + R1;
- R7 = R7 + R0 (NS) ||
- R1 = [SP];
- // Set the next AQ bit
- R1 = R7 ^ R1; // from Remainder and Y'
- R1 = R1 >> 31 || // Negate AQ's value, and
- [P5] = R1; // save next AQ
- BITTGL(R1, 0); // add neg AQ to the Div
-.LULEND: R4 = R4 + R1;
-
- R6 = [SP + 16];
-
- R0 = R4;
- R1 = R5;
- CC = BITTST(R6,30); // Just set CC=0
- R4 = ROT R0 BY 1; // but if we had to shift X,
- R5 = ROT R1 BY 1; // and didn't shift any bits out,
- CC = BITTST(R6,31); // then the result will be half as
- IF CC R0 = R4; // much as required, so shift left
- IF CC R1 = R5; // one space.
-
- SP += 20;
- (R7:4, P5:3) = [SP++];
- RTS;
-
-.Lpower_of_two:
- /* Y has a single bit set, which means it's a power of two.
- ** That means we can perform the division just by shifting
- ** X to the right the appropriate number of bits
- */
-
- /* signbits returns the number of sign bits, minus one.
- ** 1=>30, 2=>29, ..., 0x40000000=>0. Which means we need
- ** to shift right n-signbits spaces. It also means 0x80000000
- ** is a special case, because that *also* gives a signbits of 0
- */
-.Lpower_of_two_lower_zero:
- R7 = 0;
- R6 = R1 >> 31;
- CC = R3 < 0;
- IF CC JUMP .LRETURN_IDENT;
-
- R2.L = SIGNBITS R3;
- R2 = R2.L (Z);
- R2 += -62;
- (R7:4, P5:3) = [SP++];
- JUMP ___lshftli;
-
-.Lpower_of_two_upper_zero:
- CC = R2 < 0;
- IF CC JUMP .Lmaxint_shift;
-
- R2.L = SIGNBITS R2;
- R2 = R2.L (Z);
- R2 += -30;
- (R7:4, P5:3) = [SP++];
- JUMP ___lshftli;
-
-.Lmaxint_shift:
- R2 = -31;
- (R7:4, P5:3) = [SP++];
- JUMP ___lshftli;
-
-.LRETURN_IDENT:
- R0 = R6;
- R1 = R7;
-.LRETURN_R0:
- (R7:4, P5:3) = [SP++];
- RTS;
-.LDIV_BY_ZERO:
- R0 = ~R2;
- R1 = R0;
- (R7:4, P5:3) = [SP++];
- RTS;
-
-ENDPROC(___udivdi3)
-
-
-ENTRY(___lshftli)
- CC = R2 == 0;
- IF CC JUMP .Lfinished; // nothing to do
- CC = R2 < 0;
- IF CC JUMP .Lrshift;
- R3 = 64;
- CC = R2 < R3;
- IF !CC JUMP .Lretzero;
-
- // We're shifting left, and it's less than 64 bits, so
- // a valid result will be returned.
-
- R3 >>= 1; // R3 now 32
- CC = R2 < R3;
-
- IF !CC JUMP .Lzerohalf;
-
- // We're shifting left, between 1 and 31 bits, which means
- // some of the low half will be shifted into the high half.
- // Work out how much.
-
- R3 = R3 - R2;
-
- // Save that much data from the bottom half.
-
- P1 = R7;
- R7 = R0;
- R7 >>= R3;
-
- // Adjust both parts of the parameter.
-
- R0 <<= R2;
- R1 <<= R2;
-
- // And include the bits moved across.
-
- R1 = R1 | R7;
- R7 = P1;
- RTS;
-
-.Lzerohalf:
- // We're shifting left, between 32 and 63 bits, so the
- // bottom half will become zero, and the top half will
- // lose some bits. How many?
-
- R2 = R2 - R3; // N - 32
- R1 = LSHIFT R0 BY R2.L;
- R0 = R0 - R0;
- RTS;
-
-.Lretzero:
- R0 = R0 - R0;
- R1 = R0;
-.Lfinished:
- RTS;
-
-.Lrshift:
- // We're shifting right, but by how much?
- R2 = -R2;
- R3 = 64;
- CC = R2 < R3;
- IF !CC JUMP .Lretzero;
-
- // Shifting right less than 64 bits, so some result bits will
- // be retained.
-
- R3 >>= 1; // R3 now 32
- CC = R2 < R3;
- IF !CC JUMP .Lsignhalf;
-
- // Shifting right between 1 and 31 bits, so need to copy
- // data across words.
-
- P1 = R7;
- R3 = R3 - R2;
- R7 = R1;
- R7 <<= R3;
- R1 >>= R2;
- R0 >>= R2;
- R0 = R7 | R0;
- R7 = P1;
- RTS;
-
-.Lsignhalf:
- // Shifting right between 32 and 63 bits, so the top half
- // will become all zero-bits, and the bottom half is some
- // of the top half. But how much?
-
- R2 = R2 - R3;
- R0 = R1;
- R0 >>= R2;
- R1 = 0;
- RTS;
-
-ENDPROC(___lshftli)
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