foboot/sw/third_party/mul.S
Sean Cross 7210ee219d sw: add div/mul instructions
For foboot, we're using a CPU without a divide or multiply instruction,
to save gates.  Replace these with software implementations.

Signed-off-by: Sean Cross <sean@xobs.io>
2019-03-21 11:01:46 +08:00

27 lines
472 B
ArmAsm

.text
.align 2
#ifdef __riscv64
#define _RISCV_SZPTR 64
#define _RISCV_SZINT 64
#else
/* Our RV64 64-bit routine is equivalent to our RV32 32-bit routine. */
# define __muldi3 __mulsi3
#define _RISCV_SZPTR 32
#define _RISCV_SZINT 32
#endif
.globl __muldi3
__muldi3:
mv a2, a0
li a0, 0
.L1:
slli a3, a1, _RISCV_SZPTR-1
bgez a3, .L2
add a0, a0, a2
.L2:
srli a1, a1, 1
slli a2, a2, 1
bnez a1, .L1
ret