diff options
Diffstat (limited to 'sysdeps/sparc/sparc32/dotmul.S')
| -rw-r--r-- | sysdeps/sparc/sparc32/dotmul.S | 120 |
1 files changed, 3 insertions, 117 deletions
diff --git a/sysdeps/sparc/sparc32/dotmul.S b/sysdeps/sparc/sparc32/dotmul.S index d497ca672d..9b20cc3684 100644 --- a/sysdeps/sparc/sparc32/dotmul.S +++ b/sysdeps/sparc/sparc32/dotmul.S @@ -1,127 +1,13 @@ /* - * Signed multiply, from Appendix E of the Sparc Version 8 - * Architecture Manual. - */ - -/* - * Returns %o0 * %o1 in %o1%o0 (i.e., %o1 holds the upper 32 bits of - * the 64-bit product). - * - * This code optimizes short (less than 13-bit) multiplies. + * Sparc v8 has multiply. */ #include <sysdep.h> - ENTRY(.mul) - mov %o0, %y ! multiplier -> Y - andncc %o0, 0xfff, %g0 ! test bits 12..31 - be LOC(mul_shortway) ! if zero, can do it the short way - andcc %g0, %g0, %o4 ! zero the partial product and clear N and V - - /* - * Long multiply. 32 steps, followed by a final shift step. - */ - mulscc %o4, %o1, %o4 ! 1 - mulscc %o4, %o1, %o4 ! 2 - mulscc %o4, %o1, %o4 ! 3 - mulscc %o4, %o1, %o4 ! 4 - mulscc %o4, %o1, %o4 ! 5 - mulscc %o4, %o1, %o4 ! 6 - mulscc %o4, %o1, %o4 ! 7 - mulscc %o4, %o1, %o4 ! 8 - mulscc %o4, %o1, %o4 ! 9 - mulscc %o4, %o1, %o4 ! 10 - mulscc %o4, %o1, %o4 ! 11 - mulscc %o4, %o1, %o4 ! 12 - mulscc %o4, %o1, %o4 ! 13 - mulscc %o4, %o1, %o4 ! 14 - mulscc %o4, %o1, %o4 ! 15 - mulscc %o4, %o1, %o4 ! 16 - mulscc %o4, %o1, %o4 ! 17 - mulscc %o4, %o1, %o4 ! 18 - mulscc %o4, %o1, %o4 ! 19 - mulscc %o4, %o1, %o4 ! 20 - mulscc %o4, %o1, %o4 ! 21 - mulscc %o4, %o1, %o4 ! 22 - mulscc %o4, %o1, %o4 ! 23 - mulscc %o4, %o1, %o4 ! 24 - mulscc %o4, %o1, %o4 ! 25 - mulscc %o4, %o1, %o4 ! 26 - mulscc %o4, %o1, %o4 ! 27 - mulscc %o4, %o1, %o4 ! 28 - mulscc %o4, %o1, %o4 ! 29 - mulscc %o4, %o1, %o4 ! 30 - mulscc %o4, %o1, %o4 ! 31 - mulscc %o4, %o1, %o4 ! 32 - mulscc %o4, %g0, %o4 ! final shift - - ! If %o0 was negative, the result is - ! (%o0 * %o1) + (%o1 << 32)) - ! We fix that here. - -#if 0 - tst %o0 - bge 1f - rd %y, %o0 - - ! %o0 was indeed negative; fix upper 32 bits of result by subtracting - ! %o1 (i.e., return %o4 - %o1 in %o1). - retl - sub %o4, %o1, %o1 - -1: - retl - mov %o4, %o1 -#else - /* Faster code adapted from tege@sics.se's code for umul.S. */ - sra %o0, 31, %o2 ! make mask from sign bit - and %o1, %o2, %o2 ! %o2 = 0 or %o1, depending on sign of %o0 - rd %y, %o0 ! get lower half of product - retl - sub %o4, %o2, %o1 ! subtract compensation - ! and put upper half in place -#endif - -LOC(mul_shortway): - /* - * Short multiply. 12 steps, followed by a final shift step. - * The resulting bits are off by 12 and (32-12) = 20 bit positions, - * but there is no problem with %o0 being negative (unlike above). - */ - mulscc %o4, %o1, %o4 ! 1 - mulscc %o4, %o1, %o4 ! 2 - mulscc %o4, %o1, %o4 ! 3 - mulscc %o4, %o1, %o4 ! 4 - mulscc %o4, %o1, %o4 ! 5 - mulscc %o4, %o1, %o4 ! 6 - mulscc %o4, %o1, %o4 ! 7 - mulscc %o4, %o1, %o4 ! 8 - mulscc %o4, %o1, %o4 ! 9 - mulscc %o4, %o1, %o4 ! 10 - mulscc %o4, %o1, %o4 ! 11 - mulscc %o4, %o1, %o4 ! 12 - mulscc %o4, %g0, %o4 ! final shift - - /* - * %o4 has 20 of the bits that should be in the low part of the - * result; %y has the bottom 12 (as %y's top 12). That is: - * - * %o4 %y - * +----------------+----------------+ - * | -12- | -20- | -12- | -20- | - * +------(---------+------)---------+ - * --hi-- ----low-part---- - * - * The upper 12 bits of %o4 should be sign-extended to form the - * high part of the product (i.e., highpart = %o4 >> 20). - */ - rd %y, %o5 - sll %o4, 12, %o0 ! shift middle bits left 12 - srl %o5, 20, %o5 ! shift low bits right 20, zero fill at left - or %o5, %o0, %o0 ! construct low part of result + smul %o0, %o1, %o0 retl - sra %o4, 20, %o1 ! ... and extract high part of result + rd %y, %o1 END(.mul) |