diff options
Diffstat (limited to 'arch/openrisc/lib/muldi3.S')
| -rw-r--r-- | arch/openrisc/lib/muldi3.S | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/arch/openrisc/lib/muldi3.S b/arch/openrisc/lib/muldi3.S new file mode 100644 index 0000000000..902338a242 --- /dev/null +++ b/arch/openrisc/lib/muldi3.S @@ -0,0 +1,58 @@ +/* + * (C) Copyright 2011 - Franck JULLIEN <elec4fun@gmail.com> + * + * Extracted from gcc generated assembly. + * + * Multiply two quads. Hereafter, the illustration of what is going on : + * + * | r3 | r4 | + * | r5 | r6 | + * -------------------- + * | r4 * r6 | + * | r3 * r6 | | + + * | r5 * r4 | | + + * | r3 * r5 | | | + + * ------------------------------------------- = + * | 64 bits result | + * + */ + +.globl __muldi3 + +__muldi3: + /* starts with the full 64 bits mul (r4 * r6) */ + l.andi r7,r4,0xffff + l.srli r8,r4,0x10 + + l.andi r11,r6,0xffff + l.srli r12,r6,0x10 + + l.mul r13,r11,r7 + l.mul r11,r11,r8 + l.mul r7,r12,r7 + + l.srli r15,r13,0x10 + l.add r7,r7,r15 + l.add r7,r11,r7 + l.sfleu r11,r7 + l.bf no_carry + l.mul r8,r12,r8 + + l.movhi r15,0x1 + l.add r8,r8,r15 + +no_carry: + /* Now compute r3 * r6 */ + l.mul r6,r6,r3 + /* and r4 * r5 */ + l.mul r4,r4,r5 + /* finaly previous results and put the result in r11:r12 */ + l.srli r3,r7,0x10 + l.slli r7,r7,0x10 + l.andi r13,r13,0xffff + l.add r8,r8,r3 + l.add r11,r4,r6 + l.add r12,r7,r13 + l.add r11,r11,r8 + l.jr r9 + l.nop |