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|
.file "uxn-core.s"
.section .iwram, "ax", %progbits
.extern uxn_ram
.align
@
@ Core variables
@
.global wst
wst: .space 256
.global wst_ptr
wst_ptr: .word wst
.global rst
rst: .space 256
.global rst_ptr
rst_ptr: .word rst
.global io_ports
io_ports: .space 256
@
@ r0 is our custom stack pointer
@ r1 is the value we want to insert/extract
@
@ When the stack grows downwards:
@ push {r1} == str r1, [sp, #-4]!
@ pop {r1} == ldr r1, [sp], #4
@
@ In our case the stack grow upwards:
@
@ 8bit:
@ push {r1} == strb r1, [sp], #1
@ pop {r1} == ldrb r1, [sp, #-1]!
@
@ 32bit:
@ push {r1} == str r1, [sp], #4
@ pop {r1} == ldr r1, [sp, #-4]!
@
.global uxn_init_asm
uxn_init_asm:
@ DEBUG: Initialize the stack for testing purposes.
ldr r0, wst_ptr
mov r1, #4
strb r1, [r0], #1
sub r1, r1, #1
strb r1, [r0], #1
sub r1, r1, #1
strb r1, [r0], #1
sub r1, r1, #1
strb r1, [r0], #1
adr r1, wst_ptr
str r0, [r1]
bx lr
@ UXN evaluation function.
@
@ r0: PC pointer (argument is offset from RAM).
@ r1: Stack pointer (wst/rst).
@ r2: Ram ptr.
@ r3-r7: Scratch registers.
.global uxn_eval_asm
uxn_eval_asm:
@ Initialization.
push {r4-r7}
ldr r1, wst_ptr
ldr r2, =uxn_ram
add r0, r0, r2
uxn_decode:
ldrb r3, [r0], #1 @ current OP value / table index
@ TODO: Setup wst/rst? or fill operations accordingly?
@ str r3, [r1], #1 @ Push to stack: Debugging
@ Decode OP based on table lookup.
adr r4, op_table @ decoding table
ldr r4, [r4, r3, lsl #2] @ op_table[idx * 4]
bx r4 @ op_table[idx * 4]()
uxn_ret:
@ Update stack pointer and return.
adr r0, wst_ptr
str r1, [r0]
pop {r4-r7}
bx lr
@
@ OP implementations.
@
brk:
b uxn_ret
jci:
b uxn_ret
jmi:
b uxn_ret
jsi:
b uxn_ret
litr:
ldrb r3, [r0], #1
strb r3, [r1], #1
b uxn_decode
lit2r:
b uxn_ret
inc:
b uxn_ret
inc2:
b uxn_ret
pop:
b uxn_ret
pop2:
b uxn_ret
nip:
b uxn_ret
nip2:
b uxn_ret
swp:
b uxn_ret
swp2:
b uxn_ret
rot:
b uxn_ret
rot2:
b uxn_ret
dup:
b uxn_ret
dup2:
b uxn_ret
ovr:
b uxn_ret
ovr2:
b uxn_ret
equ:
b uxn_ret
equ2:
b uxn_ret
neq:
b uxn_ret
neq2:
b uxn_ret
gth:
b uxn_ret
gth2:
b uxn_ret
lth:
b uxn_ret
lth2:
b uxn_ret
jmp:
b uxn_ret
jmp2:
b uxn_ret
jcn:
b uxn_ret
jcn2:
b uxn_ret
jsr:
b uxn_ret
jsr2:
b uxn_ret
sth:
b uxn_ret
sth2:
b uxn_ret
ldz:
b uxn_ret
ldz2:
b uxn_ret
stz:
b uxn_ret
stz2:
b uxn_ret
ldr:
b uxn_ret
ldr2:
b uxn_ret
str:
b uxn_ret
str2:
b uxn_ret
lda:
b uxn_ret
lda2:
b uxn_ret
sta:
b uxn_ret
sta2:
b uxn_ret
dei:
b uxn_ret
dei2:
b uxn_ret
deo:
b uxn_ret
deo2:
b uxn_ret
add:
ldr r3, [r1, #-1]!
ldr r4, [r1, #-1]!
add r3, r3, r4
strb r3, [r1], #1
b uxn_ret @ NOTE: This should return to the next loop iteration.
add2:
b uxn_ret
sub:
@ ldr r2, [r0, #-1]!
@ ldr r1, [r0, #-1]!
@ sub r1, r1, r2
@ strb r1, [r0], #1
b uxn_ret @ NOTE: This should return to the next loop iteration.
sub2:
b uxn_ret
mul:
b uxn_ret
mul2:
b uxn_ret
div:
b uxn_ret
div2:
b uxn_ret
and:
b uxn_ret
and2:
b uxn_ret
ora:
b uxn_ret
ora2:
b uxn_ret
eor:
b uxn_ret
eor2:
b uxn_ret
sft:
b uxn_ret
sft2:
b uxn_ret
@ OP table
op_table:
.word brk @ 0x00
.word inc @ 0x01
.word pop @ 0x02
.word nip @ 0x03
.word swp @ 0x04
.word rot @ 0x05
.word dup @ 0x06
.word ovr @ 0x07
.word equ @ 0x08
.word neq @ 0x09
.word gth @ 0x0a
.word lth @ 0x0b
.word jmp @ 0x0c
.word jcn @ 0x0d
.word jsr @ 0x0e
.word sth @ 0x0f
.word ldz @ 0x00
.word stz @ 0x11
.word ldr @ 0x12
.word str @ 0x13
.word lda @ 0x14
.word sta @ 0x15
.word dei @ 0x16
.word deo @ 0x17
.word add @ 0x18
.word sub @ 0x19
.word mul @ 0x1a
.word div @ 0x1b
.word and @ 0x1c
.word ora @ 0x1d
.word eor @ 0x1e
.word sft @ 0x1f
.word brk @ 0x20
.word inc2 @ 0x21
.word pop2 @ 0x22
.word nip2 @ 0x23
.word swp2 @ 0x24
.word rot2 @ 0x25
.word dup2 @ 0x26
.word ovr2 @ 0x27
.word equ2 @ 0x28
.word neq2 @ 0x29
.word gth2 @ 0x2a
.word lth2 @ 0x2b
.word jmp2 @ 0x2c
.word jcn2 @ 0x2d
.word jsr2 @ 0x2e
.word sth2 @ 0x2f
.word ldz2 @ 0x30
.word stz2 @ 0x31
.word ldr2 @ 0x32
.word str2 @ 0x33
.word lda2 @ 0x34
.word sta2 @ 0x35
.word dei2 @ 0x36
.word deo2 @ 0x37
.word add2 @ 0x38
.word sub2 @ 0x39
.word mul2 @ 0x3a
.word div2 @ 0x3b
.word and2 @ 0x3c
.word ora2 @ 0x3d
.word eor2 @ 0x3e
.word sft2 @ 0x3f
@ TODO: Can we mask this instead of having empty space?
.word brk @ 0x40
.word brk @ 0x41
.word brk @ 0x42
.word brk @ 0x43
.word brk @ 0x44
.word brk @ 0x45
.word brk @ 0x46
.word brk @ 0x47
.word brk @ 0x48
.word brk @ 0x49
.word brk @ 0x4a
.word brk @ 0x4b
.word brk @ 0x4c
.word brk @ 0x4d
.word brk @ 0x4e
.word brk @ 0x4f
.word brk @ 0x50
.word brk @ 0x51
.word brk @ 0x52
.word brk @ 0x53
.word brk @ 0x54
.word brk @ 0x55
.word brk @ 0x56
.word brk @ 0x57
.word brk @ 0x58
.word brk @ 0x59
.word brk @ 0x5a
.word brk @ 0x5b
.word brk @ 0x5c
.word brk @ 0x5d
.word brk @ 0x5e
.word brk @ 0x5f
.word brk @ 0x60
.word brk @ 0x61
.word brk @ 0x62
.word brk @ 0x63
.word brk @ 0x64
.word brk @ 0x65
.word brk @ 0x66
.word brk @ 0x67
.word brk @ 0x68
.word brk @ 0x69
.word brk @ 0x6a
.word brk @ 0x6b
.word brk @ 0x6c
.word brk @ 0x6d
.word brk @ 0x6e
.word brk @ 0x6f
.word brk @ 0x70
.word brk @ 0x71
.word brk @ 0x72
.word brk @ 0x73
.word brk @ 0x74
.word brk @ 0x75
.word brk @ 0x76
.word brk @ 0x77
.word brk @ 0x78
.word brk @ 0x79
.word brk @ 0x7a
.word brk @ 0x7b
.word brk @ 0x7c
.word brk @ 0x7d
.word brk @ 0x7e
.word brk @ 0x7f
.word litr @ 0x80
.word brk @ 0x81
.word brk @ 0x82
.word brk @ 0x83
.word brk @ 0x84
.word brk @ 0x85
.word brk @ 0x86
.word brk @ 0x87
.word brk @ 0x88
.word brk @ 0x89
.word brk @ 0x8a
.word brk @ 0x8b
.word brk @ 0x8c
.word brk @ 0x8d
.word brk @ 0x8e
.word brk @ 0x8f
.word brk @ 0x90
.word brk @ 0x91
.word brk @ 0x92
.word brk @ 0x93
.word brk @ 0x94
.word brk @ 0x95
.word brk @ 0x96
.word brk @ 0x97
.word brk @ 0x98
.word brk @ 0x99
.word brk @ 0x9a
.word brk @ 0x9b
.word brk @ 0x9c
.word brk @ 0x9d
.word brk @ 0x9e
.word brk @ 0x9f
.word brk @ 0xa0
.word brk @ 0xa1
.word brk @ 0xa2
.word brk @ 0xa3
.word brk @ 0xa4
.word brk @ 0xa5
.word brk @ 0xa6
.word brk @ 0xa7
.word brk @ 0xa8
.word brk @ 0xa9
.word brk @ 0xaa
.word brk @ 0xab
.word brk @ 0xac
.word brk @ 0xad
.word brk @ 0xae
.word brk @ 0xaf
.word brk @ 0xb0
.word brk @ 0xb1
.word brk @ 0xb2
.word brk @ 0xb3
.word brk @ 0xb4
.word brk @ 0xb5
.word brk @ 0xb6
.word brk @ 0xb7
.word brk @ 0xb8
.word brk @ 0xb9
.word brk @ 0xba
.word brk @ 0xbb
.word brk @ 0xbc
.word brk @ 0xbd
.word brk @ 0xbe
.word brk @ 0xbf
.word brk @ 0xc0
.word brk @ 0xc1
.word brk @ 0xc2
.word brk @ 0xc3
.word brk @ 0xc4
.word brk @ 0xc5
.word brk @ 0xc6
.word brk @ 0xc7
.word brk @ 0xc8
.word brk @ 0xc9
.word brk @ 0xca
.word brk @ 0xcb
.word brk @ 0xcc
.word brk @ 0xcd
.word brk @ 0xce
.word brk @ 0xcf
.word brk @ 0xd0
.word brk @ 0xd1
.word brk @ 0xd2
.word brk @ 0xd3
.word brk @ 0xd4
.word brk @ 0xd5
.word brk @ 0xd6
.word brk @ 0xd7
.word brk @ 0xd8
.word brk @ 0xd9
.word brk @ 0xda
.word brk @ 0xdb
.word brk @ 0xdc
.word brk @ 0xdd
.word brk @ 0xde
.word brk @ 0xdf
.word brk @ 0xe0
.word brk @ 0xe1
.word brk @ 0xe2
.word brk @ 0xe3
.word brk @ 0xe4
.word brk @ 0xe5
.word brk @ 0xe6
.word brk @ 0xe7
.word brk @ 0xe8
.word brk @ 0xe9
.word brk @ 0xea
.word brk @ 0xeb
.word brk @ 0xec
.word brk @ 0xed
.word brk @ 0xee
.word brk @ 0xef
.word brk @ 0xf0
.word brk @ 0xf1
.word brk @ 0xf2
.word brk @ 0xf3
.word brk @ 0xf4
.word brk @ 0xf5
.word brk @ 0xf6
.word brk @ 0xf7
.word brk @ 0xf8
@ TODO: Can we mask this instead of having empty space?
.word lit2r @ 0xf9
.word litr @ 0xfa
.word lit2r @ 0xfb
.word litr @ 0xfc
.word jsi @ 0xfd
.word jmi @ 0xfe
.word jci @ 0xff
|