https://github.com/akkartik/mu/blob/master/201register-names.subx
  1 == data
  2 Registers:  # (addr stream {(handle array byte), int})
  3   # a table is a stream
  4   0x120/imm32/write
  5   0/imm32/read
  6   0x120/imm32/length
  7   # data
  8   # it is perfectly ok to use fake alloc-ids -- as long as you never try to reclaim them
  9   0x11/imm32/alloc-id $Register-eax/imm32 0/imm32
 10   0x11/imm32/alloc-id $Register-ecx/imm32 1/imm32
 11   0x11/imm32/alloc-id $Register-edx/imm32 2/imm32
 12   0x11/imm32/alloc-id $Register-ebx/imm32 3/imm32
 13   0x11/imm32/alloc-id $Register-esp/imm32 4/imm32
 14   0x11/imm32/alloc-id $Register-ebp/imm32 5/imm32
 15   0x11/imm32/alloc-id $Register-esi/imm32 6/imm32
 16   0x11/imm32/alloc-id $Register-edi/imm32 7/imm32
 17   # for 8-byte registers
 18   # we don't actually check if these are used when they should be; be careful
 19   0x11/imm32/alloc-id $Register-al/imm32 0/imm32
 20   0x11/imm32/alloc-id $Register-cl/imm32 1/imm32
 21   0x11/imm32/alloc-id $Register-dl/imm32 2/imm32
 22   0x11/imm32/alloc-id $Register-bl/imm32 3/imm32
 23   0x11/imm32/alloc-id $Register-ah/imm32 4/imm32
 24   0x11/imm32/alloc-id $Register-ch/imm32 5/imm32
 25   0x11/imm32/alloc-id $Register-dh/imm32 6/imm32
 26   0x11/imm32/alloc-id $Register-bh/imm32 7/imm32
 27   # for floating-point registers
 28   # we don't actually check if these are used when they should be; be careful
 29   0x11/imm32/alloc-id $Register-xmm0/imm32 0/imm32
 30   0x11/imm32/alloc-id $Register-xmm1/imm32 1/imm32
 31   0x11/imm32/alloc-id $Register-xmm2/imm32 2/imm32
 32   0x11/imm32/alloc-id $Register-xmm3/imm32 3/imm32
 33   0x11/imm32/alloc-id $Register-xmm4/imm32 4/imm32
 34   0x11/imm32/alloc-id $Register-xmm5/imm32 5/imm32
 35   0x11/imm32/alloc-id $Register-xmm6/imm32 6/imm32
 36   0x11/imm32/alloc-id $Register-xmm7/imm32 7/imm32
 37 
 38 $Register-eax:
 39   0x11/imm32/alloc-id
 40   3/imm32/size
 41   0x65/e 0x61/a 0x78/x
 42 
 43 $Register-ecx:
 44   0x11/imm32/alloc-id
 45   3/imm32/size
 46   0x65/e 0x63/c 0x78/x
 47 
 48 $Register-edx:
 49   0x11/imm32/alloc-id
 50   3/imm32/size
 51   0x65/e 0x64/d 0x78/x
 52 
 53 $Register-ebx:
 54   0x11/imm32/alloc-id
 55   3/imm32/size
 56   0x65/e 0x62/b 0x78/x
 57 
 58 $Register-esp:
 59   0x11/imm32/alloc-id
 60   3/imm32/size
 61   0x65/e 0x73/s 0x70/p
 62 
 63 $Register-ebp:
 64   0x11/imm32/alloc-id
 65   3/imm32/size
 66   0x65/e 0x62/b 0x70/p
 67 
 68 $Register-esi:
 69   0x11/imm32/alloc-id
 70   3/imm32/size
 71   0x65/e 0x73/s 0x69/i
 72 
 73 $Register-edi:
 74   0x11/imm32/alloc-id
 75   3/imm32/size
 76   0x65/e 0x64/d 0x69/i
 77 
 78 $Register-al:
 79   0x11/imm32/alloc-id
 80   2/imm32/size
 81   0x61/a 0x6c/l
 82 
 83 $Register-cl:
 84   0x11/imm32/alloc-id
 85   2/imm32/size
 86   0x63/c 0x6c/l
 87 
 88 $Register-dl:
 89   0x11/imm32/alloc-id
 90   2/imm32/size
 91   0x64/d 0x6c/l
 92 
 93 $Register-bl:
 94   0x11/imm32/alloc-id
 95   2/imm32/size
 96   0x62/b 0x6c/l
 97 
 98 $Register-ah:
 99   0x11/imm32/alloc-id
100   2/imm32/size
101   0x61/a 0x68/h
102 
103 $Register-ch:
104   0x11/imm32/alloc-id
105   2/imm32/size
106   0x63/c 0x68/h
107 
108 $Register-dh:
109   0x11/imm32/alloc-id
110   2/imm32/size
111   0x64/d 0x68/h
112 
113 $Register-bh:
114   0x11/imm32/alloc-id
115   2/imm32/size
116   0x62/b 0x68/h
117 
118 $Register-xmm0:
119   0x11/imm32/alloc-id:fake:payload
120   # "xmm0"
121   0x4/imm32/size
122   0x78/x 0x6d/m 0x6d/m 0x30/0
123 
124 $Register-xmm1:
125   0x11/imm32/alloc-id:fake:payload
126   # "xmm1"
127   0x4/imm32/size
128   0x78/x 0x6d/m 0x6d/m 0x31/1
129 
130 $Register-xmm2:
131   0x11/imm32/alloc-id:fake:payload
132   # "xmm2"
133   0x4/imm32/size
134   0x78/x 0x6d/m 0x6d/m 0x32/2
135 
136 $Register-xmm3:
137   0x11/imm32/alloc-id:fake:payload
138   # "xmm3"
139   0x4/imm32/size
140   0x78/x 0x6d/m 0x6d/m 0x33/3
141 
142 $Register-xmm4:
143   0x11/imm32/alloc-id:fake:payload
144   # "xmm4"
145   0x4/imm32/size
146   0x78/x 0x6d/m 0x6d/m 0x34/4
147 
148 $Register-xmm5:
149   0x11/imm32/alloc-id:fake:payload
150   # "xmm5"
151   0x4/imm32/size
152   0x78/x 0x6d/m 0x6d/m 0x35/5
153 
154 $Register-xmm6:
155   0x11/imm32/alloc-id:fake:payload
156   # "xmm6"
157   0x4/imm32/size
158   0x78/x 0x6d/m 0x6d/m 0x36/6
159 
160 $Register-xmm7:
161   0x11/imm32/alloc-id:fake:payload
162   # "xmm7"
163   0x4/imm32/size
164   0x78/x 0x6d/m 0x6d/m 0x37/7