--- /dev/null
+ .file "wm_shrx.S"
+/*---------------------------------------------------------------------------+
+ | wm_shrx.S |
+ | |
+ | 64 bit right shift functions |
+ | |
+ | Copyright (C) 1992,1995 |
+ | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
+ | Australia. E-mail billm@jacobi.maths.monash.edu.au |
+ | |
+ | Call from C as: |
+ | unsigned FPU_shrx(void *arg1, unsigned arg2) |
+ | and |
+ | unsigned FPU_shrxs(void *arg1, unsigned arg2) |
+ | |
+ +---------------------------------------------------------------------------*/
+
+#include "fpu_emu.h"
+
+.text
+/*---------------------------------------------------------------------------+
+ | unsigned FPU_shrx(void *arg1, unsigned arg2) |
+ | |
+ | Extended shift right function. |
+ | Fastest for small shifts. |
+ | Shifts the 64 bit quantity pointed to by the first arg (arg1) |
+ | right by the number of bits specified by the second arg (arg2). |
+ | Forms a 96 bit quantity from the 64 bit arg and eax: |
+ | [ 64 bit arg ][ eax ] |
+ | shift right ---------> |
+ | The eax register is initialized to 0 before the shifting. |
+ | Results returned in the 64 bit arg and eax. |
+ +---------------------------------------------------------------------------*/
+
+ENTRY(FPU_shrx)
+ push %ebp
+ movl %esp,%ebp
+ pushl %esi
+ movl PARAM2,%ecx
+ movl PARAM1,%esi
+ cmpl $32,%ecx /* shrd only works for 0..31 bits */
+ jnc L_more_than_31
+
+/* less than 32 bits */
+ pushl %ebx
+ movl (%esi),%ebx /* lsl */
+ movl 4(%esi),%edx /* msl */
+ xorl %eax,%eax /* extension */
+ shrd %cl,%ebx,%eax
+ shrd %cl,%edx,%ebx
+ shr %cl,%edx
+ movl %ebx,(%esi)
+ movl %edx,4(%esi)
+ popl %ebx
+ popl %esi
+ leave
+ ret
+
+L_more_than_31:
+ cmpl $64,%ecx
+ jnc L_more_than_63
+
+ subb $32,%cl
+ movl (%esi),%eax /* lsl */
+ movl 4(%esi),%edx /* msl */
+ shrd %cl,%edx,%eax
+ shr %cl,%edx
+ movl %edx,(%esi)
+ movl $0,4(%esi)
+ popl %esi
+ leave
+ ret
+
+L_more_than_63:
+ cmpl $96,%ecx
+ jnc L_more_than_95
+
+ subb $64,%cl
+ movl 4(%esi),%eax /* msl */
+ shr %cl,%eax
+ xorl %edx,%edx
+ movl %edx,(%esi)
+ movl %edx,4(%esi)
+ popl %esi
+ leave
+ ret
+
+L_more_than_95:
+ xorl %eax,%eax
+ movl %eax,(%esi)
+ movl %eax,4(%esi)
+ popl %esi
+ leave
+ ret
+
+
+/*---------------------------------------------------------------------------+
+ | unsigned FPU_shrxs(void *arg1, unsigned arg2) |
+ | |
+ | Extended shift right function (optimized for small floating point |
+ | integers). |
+ | Shifts the 64 bit quantity pointed to by the first arg (arg1) |
+ | right by the number of bits specified by the second arg (arg2). |
+ | Forms a 96 bit quantity from the 64 bit arg and eax: |
+ | [ 64 bit arg ][ eax ] |
+ | shift right ---------> |
+ | The eax register is initialized to 0 before the shifting. |
+ | The lower 8 bits of eax are lost and replaced by a flag which is |
+ | set (to 0x01) if any bit, apart from the first one, is set in the |
+ | part which has been shifted out of the arg. |
+ | Results returned in the 64 bit arg and eax. |
+ +---------------------------------------------------------------------------*/
+ENTRY(FPU_shrxs)
+ push %ebp
+ movl %esp,%ebp
+ pushl %esi
+ pushl %ebx
+ movl PARAM2,%ecx
+ movl PARAM1,%esi
+ cmpl $64,%ecx /* shrd only works for 0..31 bits */
+ jnc Ls_more_than_63
+
+ cmpl $32,%ecx /* shrd only works for 0..31 bits */
+ jc Ls_less_than_32
+
+/* We got here without jumps by assuming that the most common requirement
+ is for small integers */
+/* Shift by [32..63] bits */
+ subb $32,%cl
+ movl (%esi),%eax /* lsl */
+ movl 4(%esi),%edx /* msl */
+ xorl %ebx,%ebx
+ shrd %cl,%eax,%ebx
+ shrd %cl,%edx,%eax
+ shr %cl,%edx
+ orl %ebx,%ebx /* test these 32 bits */
+ setne %bl
+ test $0x7fffffff,%eax /* and 31 bits here */
+ setne %bh
+ orw %bx,%bx /* Any of the 63 bit set ? */
+ setne %al
+ movl %edx,(%esi)
+ movl $0,4(%esi)
+ popl %ebx
+ popl %esi
+ leave
+ ret
+
+/* Shift by [0..31] bits */
+Ls_less_than_32:
+ movl (%esi),%ebx /* lsl */
+ movl 4(%esi),%edx /* msl */
+ xorl %eax,%eax /* extension */
+ shrd %cl,%ebx,%eax
+ shrd %cl,%edx,%ebx
+ shr %cl,%edx
+ test $0x7fffffff,%eax /* only need to look at eax here */
+ setne %al
+ movl %ebx,(%esi)
+ movl %edx,4(%esi)
+ popl %ebx
+ popl %esi
+ leave
+ ret
+
+/* Shift by [64..95] bits */
+Ls_more_than_63:
+ cmpl $96,%ecx
+ jnc Ls_more_than_95
+
+ subb $64,%cl
+ movl (%esi),%ebx /* lsl */
+ movl 4(%esi),%eax /* msl */
+ xorl %edx,%edx /* extension */
+ shrd %cl,%ebx,%edx
+ shrd %cl,%eax,%ebx
+ shr %cl,%eax
+ orl %ebx,%edx
+ setne %bl
+ test $0x7fffffff,%eax /* only need to look at eax here */
+ setne %bh
+ orw %bx,%bx
+ setne %al
+ xorl %edx,%edx
+ movl %edx,(%esi) /* set to zero */
+ movl %edx,4(%esi) /* set to zero */
+ popl %ebx
+ popl %esi
+ leave
+ ret
+
+Ls_more_than_95:
+/* Shift by [96..inf) bits */
+ xorl %eax,%eax
+ movl (%esi),%ebx
+ orl 4(%esi),%ebx
+ setne %al
+ xorl %ebx,%ebx
+ movl %ebx,(%esi)
+ movl %ebx,4(%esi)
+ popl %ebx
+ popl %esi
+ leave
+ ret
Code Review / kvmfornfv.git / blobdiff