.global u64hex
.global u32hex
.global u8hex

.macro hexnibble src, shift, dest
    slli t1, \src, 64-\shift-4 # put high nibble of s7 in t1
    srli t1, t1, 64-4
    addi t2, t1, 0x30 # convert to decimal digit
    bgt t5, t1, 0f # if digit >= 10, switch to alpha
    addi t2, t1, 0x61-10
0:
    # copy digit to writebuf
    sb t2, \dest
.endm

.macro hexbyte src, shift, dest
    hexnibble \src, (\shift+4), \dest
    hexnibble \src, \shift, 1+\dest
.endm

# arguments:
# a0 - buffer (8, 16 bytes)
# a1 - int (32, 64 bits)
#
# clobbers: t1, t2, t5
# leaves a0 and a1 unchanged

u64hex:
    li t5, 10
    hexbyte a1, 56, 0(a0)
    hexbyte a1, 48, 2(a0)
    hexbyte a1, 40, 4(a0)
    hexbyte a1, 32, 6(a0)
    hexbyte a1, 24, 8(a0)
    hexbyte a1, 16, 10(a0)
    hexbyte a1,  8, 12(a0)
    hexbyte a1,  0, 14(a0)
    ret

u32hex:
    li t5, 10
    hexbyte a1, 24, 0(a0)
    hexbyte a1, 16, 2(a0)
    hexbyte a1, 8, 4(a0)
    hexbyte a1, 0, 6(a0)
    ret

u8hex:
    li t5, 10
    hexbyte s7, 0, 6(a0)
    ret