forked from TCShenanigans/symphony_stdlib
146 lines
2.7 KiB
NASM
146 lines
2.7 KiB
NASM
; Convert string to integer
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; Arguments:
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; r1 - Pointer to string
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; Result:
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; r1 - Parsed integer
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; r2 - Pointer to first rejected input byte
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; Clobbers:
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; flags
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; r3 - last character read
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; Note: Unless the input is "0", tail-calls into a base-specific specialization.
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pub atoi:
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load_8 r3, [r1]
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cmp r3, 0x30 ; '0'
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jne atoi_dec ; No prefix, parse decimal
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add r1, r1, 1
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load_8 r3, [r1] ; From "boxBOX", or an octal digit
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cmp r3, 0x30 ; '0'
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jl atoi_badprefix
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cmp r3, 0x37 ; '7'
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jle atoi_oct
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add r1, r1, 1 ; Not octal; 2-byte prefix
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and r3, r3, 0x5f ; to uppercase
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cmp r3, 0x42 ; 'B'
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je atoi_bin
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cmp r3, 0x4F ; 'O'
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je atoi_oct
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cmp r3, 0x58 ; 'X'
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je atoi_hex
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; not a valid prefix, but we did see a zero
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atoi_badprefix:
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mov r2, r1
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mov r1, 0
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; Only exists because conditional register jumps are not allowed
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atoi_done:
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jmp r13
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; Convert decimal string to integer
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; Arguments:
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; r1 - Pointer to string
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; Result:
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; r1 - Parsed integer
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; r2 - Pointer to first rejected input byte
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; Clobbers:
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; flags
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; r3 - last character read
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pub atoi_dec:
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mov r2, r1
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mov r1, 0
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atoi_dec_loop:
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load_8 r3, [r2]
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cmp r3, 0x30 ; '0'
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jl atoi_done
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cmp r3, 0x39 ; '9'
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jg atoi_done
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add r2, r2, 1
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sub r3, r3, 0x30 ; '0'
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lsl flags, r1, 2
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add r1, r1, flags
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lsl r1, r1, 1
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add r1, r1, r3
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jmp atoi_dec_loop
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; Convert binary string to integer
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; Arguments:
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; r1 - Pointer to string
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; Result:
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; r1 - Parsed integer
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; r2 - Pointer to first rejected input byte
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; Clobbers:
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; flags
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; r3 - last character read
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pub atoi_bin:
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mov r2, r1
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mov r1, 0
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atoi_bin_loop:
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load_8 r3, [r2]
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cmp r3, 0x30 ; '0'
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jl atoi_done
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cmp r3, 0x39 ; '1'
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jg atoi_done
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add r2, r2, 1
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sub r3, r3, 0x30 ; '0'
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lsl r1, r1, 1
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add r1, r1, r3
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jmp atoi_bin_loop
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; Convert octal string to integer
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; Arguments:
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; r1 - Pointer to string
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; Result:
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; r1 - Parsed integer
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; r2 - Pointer to first rejected input byte
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; Clobbers:
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; flags
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; r3 - last character read
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pub atoi_oct:
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mov r2, r1
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mov r1, 0
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atoi_oct_loop:
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load_8 r3, [r2]
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cmp r3, 0x30 ; '0'
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jl atoi_done
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cmp r3, 0x37 ; '7'
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jg atoi_done
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add r2, r2, 1
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sub r3, r3, 0x30 ; '0'
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lsl r1, r1, 3
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add r1, r1, r3
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jmp atoi_oct_loop
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; Convert hexadecimal string to integer
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; Arguments:
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; r1 - Pointer to string
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; Result:
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; r1 - Parsed integer
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; r2 - Pointer to first rejected input byte
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; Clobbers:
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; flags
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; r3 - last character read
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pub atoi_hex:
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mov r2, r1
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mov r1, 0
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atoi_hex_loop:
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load_8 r3, [r2]
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cmp r3, 0x30 ; '0'
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jl atoi_done
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cmp r3, 0x39 ; '9'
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jg atoi_hex_letter
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add r2, r2, 1
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sub r3, r3, 0x30 ; '0'
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lsl r1, r1, 4
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add r1, r1, r3
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jmp atoi_hex_loop
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atoi_hex_letter:
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and r3, r3, 0x5f ; to uppercase
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cmp r3, 0x41 ; 'A'
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jl atoi_done
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cmp r3, 0x46 ; 'F'
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jg atoi_done
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add r2, r2, 1
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sub r3, r3, 0x37 ; 'A' - 10
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lsl r1, r1, 4
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add r1, r1, r3
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jmp atoi_hex_loop |