Initial version of atoi

Functions to convert strings to integers in various bases
2026-09-02 21:14:04 +02:00
parent 37d0e556d2
commit 1d04812174
3 changed files with 232 additions and 0 deletions
@@ -0,0 +1,145 @@
+; Convert string to integer
+; Arguments:
+; r1 - Pointer to string
+; Result:
+; r1 - Parsed integer
+; r2 - Pointer to first rejected input byte
+; Clobbers:
+; flags
+; r3 - last character read
+pub fn_atoi:
+load_8 r3, [r1]
+cmp r3, 0x30 ; '0'
+jne fn_atoi_dec ; No prefix, parse decimal
+add r1, r1, 1
+load_8 r3, [r1] ; From "boxBOX", or an octal digit
+cmp r3, 0x30 ; '0'
+jl atoi_badprefix
+cmp r3, 0x37 ; '7'
+jle fn_atoi_oct
+add r1, r1, 1 ; Not octal; 2-byte prefix 
+and r3, r3, 0x5f ; to uppercase
+cmp r3, 0x42 ; 'B'
+je fn_atoi_bin
+cmp r3, 0x4F ; 'O'
+je fn_atoi_oct
+cmp r3, 0x58 ; 'X'
+je fn_atoi_hex
+
+; not a valid prefix, but we did see a zero
+atoi_badprefix:
+mov r2, r1
+mov r1, 0
+; Only exists because conditional register jumps are not allowed
+atoi_done:
+jmp r13
+
+; Convert decimal string to integer
+; Arguments:
+; r1 - Pointer to string
+; Result:
+; r1 - Parsed integer
+; r2 - Pointer to first rejected input byte
+; Clobbers:
+; flags
+; r3 - last character read
+pub fn_atoi_dec:
+mov r2, r1
+mov r1, 0
+atoi_dec_loop:
+load_8 r3, [r2]
+cmp r3, 0x30 ; '0'
+jl atoi_done
+cmp r3, 0x39 ; '9'
+jg atoi_done
+add r2, r2, 1
+sub r3, r3, 0x30 ; '0'
+lsl flags, r1, 2
+add r1, r1, flags
+lsl r1, r1, 1
+add r1, r1, r3
+jmp atoi_dec_loop
+
+; Convert binary string to integer
+; Arguments:
+; r1 - Pointer to string
+; Result:
+; r1 - Parsed integer
+; r2 - Pointer to first rejected input byte
+; Clobbers:
+; flags
+; r3 - last character read
+pub fn_atoi_bin:
+mov r2, r1
+mov r1, 0
+atoi_bin_loop:
+load_8 r3, [r2]
+cmp r3, 0x30 ; '0'
+jl atoi_done
+cmp r3, 0x39 ; '1'
+jg atoi_done
+add r2, r2, 1
+sub r3, r3, 0x30 ; '0'
+lsl r1, r1, 1
+add r1, r1, r3
+jmp atoi_bin_loop
+
+; Convert octal string to integer
+; Arguments:
+; r1 - Pointer to string
+; Result:
+; r1 - Parsed integer
+; r2 - Pointer to first rejected input byte
+; Clobbers:
+; flags
+; r3 - last character read
+pub fn_atoi_oct:
+mov r2, r1
+mov r1, 0
+atoi_oct_loop:
+load_8 r3, [r2]
+cmp r3, 0x30 ; '0'
+jl atoi_done
+cmp r3, 0x39 ; '7'
+jg atoi_done
+add r2, r2, 1
+sub r3, r3, 0x30 ; '0'
+lsl r1, r1, 3
+add r1, r1, r3
+jmp atoi_oct_loop
+
+; Convert hexadecimal string to integer
+; Arguments:
+; r1 - Pointer to string
+; Result:
+; r1 - Parsed integer
+; r2 - Pointer to first rejected input byte
+; Clobbers:
+; flags
+; r3 - last character read
+pub fn_atoi_hex:
+mov r2, r1
+mov r1, 0
+atoi_hex_loop:
+load_8 r3, [r2]
+cmp r3, 0x30 ; '0'
+jl atoi_done
+cmp r3, 0x39 ; '9'
+jg atoi_hex_letter
+add r2, r2, 1
+sub r3, r3, 0x30 ; '0'
+lsl r1, r1, 4
+add r1, r1, r3
+jmp atoi_hex_loop
+
+atoi_hex_letter:
+and r3, r3, 0x5f ; to uppercase
+cmp r3, 0x41 ; 'A'
+jl atoi_done
+cmp r3, 0x46 ; 'F'
+jg atoi_done
+add r2, r2, 1
+sub r3, r3, 0x37 ; 'A' - 10
+lsl r1, r1, 4
+add r1, r1, r3
+jmp atoi_hex_loop