diff options
Diffstat (limited to 'lib/i386/ashrdi3.s')
-rw-r--r-- | lib/i386/ashrdi3.s | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/lib/i386/ashrdi3.s b/lib/i386/ashrdi3.s new file mode 100644 index 000000000..db01f2132 --- /dev/null +++ b/lib/i386/ashrdi3.s @@ -0,0 +1,75 @@ +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. + +// di_int __ashrdi3(di_int input, int count); + +#ifdef __i386__ +#ifdef __SSE2__ + +.text +.align 4 +.globl ___ashrdi3 +___ashrdi3: + movd 12(%esp), %xmm2 // Load count + movl 8(%esp), %eax +#ifndef TRUST_CALLERS_USE_64_BIT_STORES + movd 4(%esp), %xmm0 + movd 8(%esp), %xmm1 + punpckldq %xmm1, %xmm0 // Load input +#else + movq 4(%esp), %xmm0 // Load input +#endif + + psrlq %xmm2, %xmm0 // unsigned shift input by count + + testl %eax, %eax // check the sign-bit of the input + jns 1f // early out for positive inputs + + // If the input is negative, we need to construct the shifted sign bit + // to or into the result, as xmm does not have a signed right shift. + pcmpeqb %xmm1, %xmm1 // -1ULL + psrlq $58, %xmm1 // 0x3f + pandn %xmm1, %xmm2 // 63 - count + pcmpeqb %xmm1, %xmm1 // -1ULL + psubq %xmm1, %xmm2 // 64 - count + psllq %xmm2, %xmm1 // -1 << (64 - count) = leading sign bits + por %xmm1, %xmm0 + + // Move the result back to the general purpose registers and return +1: movd %xmm0, %eax + psrlq $32, %xmm0 + movd %xmm0, %edx + ret + +#else // Use GPRs instead of SSE2 instructions, if they aren't available. + +.text +.align 4 +.globl ___ashrdi3 +___ashrdi3: + movl 12(%esp), %ecx // Load count + movl 8(%esp), %edx // Load high + movl 4(%esp), %eax // Load low + + testl $0x20, %ecx // If count >= 32 + jnz 2f // goto 2 + testl $0x1f, %ecx // If count == 0 + jz 1f // goto 1 + + pushl %ebx + movl %edx, %ebx // copy high + shrl %cl, %eax // right shift low by count + sarl %cl, %edx // right shift high by count + neg %cl + shll %cl, %ebx // left shift high by 32 - count + orl %ebx, %eax // or the result into the low word + popl %ebx +1: ret + +2: movl %edx, %eax // Move high to low + sarl $31, %edx // clear high + sarl %cl, %eax // shift low by count - 32 + ret + +#endif // __SSE2__ +#endif // __i386__ |