157 lines
2.5 KiB
Plaintext
157 lines
2.5 KiB
Plaintext
; The OS/K Team licenses this file to you under the MIT license.
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; See the LICENSE file in the project root for more information.
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;
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; int strtol(const char *str, int base)
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;
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; rax = integer extracted from str
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; rdx = pointer to first invalid byte
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;
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strtol:
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mov ax2, 1
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jmp strtoq
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;
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; int strtoul(const char *str, int base)
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;
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; rax = integer extracted from str
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; rdx = pointer to first invalid byte
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;
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strtoul:
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mov ax2, zero
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jmp strtoq
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;
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; int strtoq(const char *str, int base, bool signed)
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;
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; guesses base when 'base'=0
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;
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strtoq:
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mov rax, zero
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mov rdx, ax0
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; make sure base is in [2, 32]
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b.z ax1, 1, .bad
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b.a ax1, 36, .bad
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; empty string?
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b.z b[rdx], zero, .done
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.skip_spc:
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cmp b[rdx], ' '
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add.z rdx, rdx, 1
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jmp.z .skip_spc
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; skip +
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cmp b[rdx], '+'
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add.z rdx, rdx, 1
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; signed?
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cmp ax2, zero
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mov.z rsi, zero
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jmp.z .unsigned
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; parse '-'
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cmp b[rdx], '-'
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add.z rdx, rdx, 1
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mov.z rsi, 1
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mov.nz rsi, zero
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.unsigned:
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; base 0
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b.z ax1, 0, .base_0
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; base prefix?
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b.nz b[rdx], '0', .main_loop
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add rdx, rdx, 1
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movzx rcx, b[rdx]
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; "0x"/"0b" prefix
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jmp.cxz .done ; "0"
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b.z rcx, 'x', .parsed_0x
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b.z rcx, 'b', .parsed_0b
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; may be octal, but we don't care
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; we accept "0110101010" (despite base=2) for instance
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jmp .main_loop
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.parsed_0x:
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; are we in base 16?
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; if not, leave rax = 0 and *rdx = 'x'
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b.nz ax1, 16, .done
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; else
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add rdx, rdx, 1
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jmp .main_loop
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.parsed_0b:
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; are we in base 2?
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; if not, leave rax = 0 and *rdx = 'b'
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b.nz ax1, 2, .done
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; else
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add rdx, rdx, 1
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jmp .main_loop
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.base_0:
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; guess base
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cmp b[rdx], '0'
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mov.nz ax1, 10
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jmp.nz .main_loop
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add rdx, rdx, 1
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cmp b[rdx], 'x'
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add.z rdx, rdx, 1
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mov.z ax1, 16
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jmp.z .main_loop
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cmp b[rdx], 'b'
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add.z rdx, rdx, 1
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mov.z ax1, 2
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jmp.z .main_loop
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mov ax1, 8
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.main_loop:
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movzx rcx, b[rdx]
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add rdx, rdx, 1
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cmp rcx, '0'
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jmp.b .done
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cmp.ae rcx, '9'
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sub.be rcx, rcx, '0'
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jmp.be .next
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cmp rcx, 'A'
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cmp.ae rcx, 'Z'
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sub.be rcx, rcx, 55 ; 'A' - 10
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jmp.be .next
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cmp rcx, 'a'
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jmp.b .next
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cmp.ae rcx, 'z'
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sub.be rcx, rcx, 87 ; 'a' - 10
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jmp.be .next
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.next:
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; too large for base?
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b.ae rcx, ax1, .done
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mul rax, rax, ax1
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add rax, rax, rcx
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jmp .main_loop
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.done:
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; negative?
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cmp rsi, zero
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ret.z
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; yes
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sub rax, zero, rax
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ret
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.bad:
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mov q[errno], EINVAL
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ret
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