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dev: started to add OS functions

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This commit is contained in:
A.M. Rowsell 2026-01-12 13:09:50 -05:00
commit fc244f8481
Signed by: amr
GPG key ID: E0879EDBDB0CA7B1
4 changed files with 1607 additions and 1474 deletions
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8
Makefile
View file

@ -6,9 +6,12 @@ MAP=zone.map
ASMFLAGS=-Fvobj
LINKFLAGS=-b ihex -T linker.cmd -M
BINLINKFLAGS=-b rawbin -T linker.cmd -M
all: zone.hex
binary: zone.bin
float.o: float.asm
$(ASM) $(ASMFLAGS) -o $@ $<
@ -24,7 +27,10 @@ boot.o: boot.asm
zone.hex: float.o vectorTable.o zone.o boot.o linker.cmd
$(LINK) $(LINKFLAGS) -o $@ float.o vectorTable.o zone.o boot.o > $(MAP)
zone.bin: float.o vectorTable.o zone.o boot.o linker.cmd
$(LINK) $(BINLINKFLAGS) -o $@ float.o vectorTable.o zone.o boot.o > $(MAP)
clean:
rm -f float.o vectorTable.o zone.o boot.o zone.hex $(MAP)
rm -f float.o vectorTable.o zone.o boot.o zone.hex zone.bin $(MAP)
.PHONY: all clean

1
boot.asm
View file

@ -9,6 +9,7 @@
; This is the cold boot entry point!
; It is linked to land at 0xC3C3
; ==================================
_start:
zone_setup:
ld sp, 0x6FFF
jp os_main_loop

171
float.asm
View file

@ -8,11 +8,11 @@
; byte1: S|F22..F16 (bit7 = sign, bits6..0 = top 7 fraction bits)
; byte2: F15..F8
; byte3: F7..F0
;
; For EXP != 0:
; value = (-1)^S * (1.F) * 2^(EXP - FP_BIAS)
; FP_BIAS = 127
;
; Calling convention (in-place ops):
; HL -> A (4 bytes)
; DE -> B (4 bytes)
@ -20,11 +20,11 @@
; fp_sub: A = A - B
; fp_mul: A = A * B
; fp_div: A = A / B
;
; Extra:
; fp_print: print float at (HL) using external os_print_vec (A=ASCII)
; fp_parse: parse null-terminated string at (DE) into float at (HL)
;
; Limitations:
; - No NaN/Inf/denormals
; - Truncation (no rounding)
@ -54,6 +54,7 @@
; ------------------------------------------------------------
; fp_add: A = A + B
; ------------------------------------------------------------
fp_add:
push hl
push de
@ -69,6 +70,7 @@ fp_add:
; A==0 => result=B
call fp_pack_from_B_into_A
ret
fp_add_checkB:
ld a, (B_exp)
or a
@ -84,10 +86,10 @@ fp_add_checkB:
; signs differ -> magnitude subtract
jp fp_add_diff_sign
; ------------------------------------------------------------
; fp_sub: A = A - B (flip B sign in memory, add, flip back)
; ------------------------------------------------------------
fp_sub:
; Flip sign bit of B byte1 (DE+1)
push hl
@ -112,10 +114,10 @@ fp_sub:
pop hl
ret
; ------------------------------------------------------------
; fp_mul: A = A * B
; ------------------------------------------------------------
fp_mul:
push hl
push de
@ -157,10 +159,10 @@ fp_mul:
call fp_packA
ret
; ------------------------------------------------------------
; fp_div: A = A / B
; ------------------------------------------------------------
fp_div:
push hl
push de
@ -203,7 +205,6 @@ fp_div:
call fp_packA
ret
; ============================================================
; Add/Sub core (unpacked)
; ============================================================
@ -218,18 +219,19 @@ fp_add_same_sign:
ld a, (A_exp)
inc a
ld (A_exp), a
fp_add_same_sign_noCarry:
call normalize_A_mant
call fp_packA
ret
fp_add_diff_sign:
; compare |A| vs |B|, do larger - smaller, sign = sign(larger)
call compare_mag_A_B
jr c, fp_add_diff_sign_A_ge_B
; |B| > |A| => swap
call swap_A_B_unpacked
fp_add_diff_sign_A_ge_B:
call align_exponents_A_B
call sub24_A_minus_B
@ -239,12 +241,12 @@ fp_add_diff_sign_A_ge_B:
call fp_packA
ret
; ============================================================
; Unpack / Pack helpers
; ============================================================
; Unpack A from (HL)
fp_unpackA:
ld a, (hl)
ld (A_exp), a
@ -258,8 +260,10 @@ fp_unpackA:
jp z, fp_unpackA_sa0
ld a, 1
jr fp_unpackA_sa1
fp_unpackA_sa0:
xor a
fp_unpackA_sa1:
ld (A_sign), a
@ -275,6 +279,7 @@ fp_unpackA_sa1:
ld a, (hl)
ld (A_m0), a
ret
fp_unpackA_zeroA:
xor a
ld (A_sign), a
@ -283,8 +288,8 @@ fp_unpackA_zeroA:
ld (A_m0), a
ret
; Unpack B from (DE)
fp_unpackB:
ld a, (de)
ld (B_exp), a
@ -297,8 +302,10 @@ fp_unpackB:
jp z, fp_unpackB_sb0
ld a, 1
jr fp_unpackB_sb1
fp_unpackB_sb0:
xor a
fp_unpackB_sb1:
ld (B_sign), a
@ -313,6 +320,7 @@ fp_unpackB_sb1:
ld a, (de)
ld (B_m0), a
ret
fp_unpackB_zeroB:
xor a
ld (B_sign), a
@ -321,8 +329,8 @@ fp_unpackB_zeroB:
ld (B_m0), a
ret
; Pack unpacked A back into memory at (HL)
fp_packA:
ld a, (A_exp)
or a
@ -354,8 +362,10 @@ fp_packA_packNZ:
ld a, b
or 0x80
jr fp_packA_storeB1
fp_packA_sign0:
ld a, b
fp_packA_storeB1:
ld (hl), a
inc hl
@ -366,8 +376,8 @@ fp_packA_storeB1:
ld (hl), a
ret
; Pack from unpacked B into memory A (HL points to A destination)
fp_pack_from_B_into_A:
ld a, (B_exp)
ld (hl), a
@ -381,8 +391,10 @@ fp_pack_from_B_into_A:
ld a, b
or 0x80
jr fp_pack_from_B_bs1
fp_pack_from_B_bs0:
ld a, b
fp_pack_from_B_bs1:
ld (hl), a
inc hl
@ -393,7 +405,6 @@ fp_pack_from_B_bs1:
ld (hl), a
ret
fp_store_zero_A:
xor a
ld (A_exp), a
@ -403,12 +414,12 @@ fp_store_zero_A:
ld (A_m0), a
jp fp_packA
; ============================================================
; Exponent alignment / compare / swap
; ============================================================
; Ensure A_exp >= B_exp; shift smaller mantissa right by diff
align_exponents_A_B:
ld a, (A_exp)
ld b, a
@ -417,6 +428,7 @@ align_exponents_A_B:
jr z, align_exponents_A_B_done
jr c, align_exponents_A_B_bigger_exp; B_exp < A_exp
call swap_A_B_unpacked; make A the larger exponent
align_exponents_A_B_bigger_exp:
ld a, (A_exp)
ld b, a
@ -427,11 +439,12 @@ align_exponents_A_B_bigger_exp:
call shr24_B_by_A
ld a, (A_exp)
ld (B_exp), a
align_exponents_A_B_done:
ret
; Carry set if |A| >= |B|, else carry clear
compare_mag_A_B:
ld a, (A_exp)
ld b, a
@ -441,9 +454,11 @@ compare_mag_A_B:
jr c, compare_mag_A_B_ge
or a
ret
compare_mag_A_B_ge:
scf
ret
compare_mag_A_B_cmpMant:
ld a, (A_m2)
ld b, a
@ -453,9 +468,11 @@ compare_mag_A_B_cmpMant:
jr c, compare_mag_A_B_ge2
or a
ret
compare_mag_A_B_ge2:
scf
ret
compare_mag_A_B_m1:
ld a, (A_m1)
ld b, a
@ -465,9 +482,11 @@ compare_mag_A_B_m1:
jr c, compare_mag_A_B_ge3
or a
ret
compare_mag_A_B_ge3:
scf
ret
compare_mag_A_B_m0:
ld a, (A_m0)
ld b, a
@ -476,11 +495,11 @@ compare_mag_A_B_m0:
jr c, compare_mag_A_B_ge4
scf
ret
compare_mag_A_B_ge4:
scf
ret
swap_A_B_unpacked:
ld a, (A_exp)
ld b, a
@ -514,7 +533,6 @@ swap_A_B_unpacked:
ld (B_m0), a
ret
; ============================================================
; 24-bit mantissa ops
; ============================================================
@ -537,7 +555,6 @@ add24_A_plus_B:
ld (A_m2), a
ret ; carry meaningful
sub24_A_minus_B:
ld a, (B_m0)
ld b, a
@ -556,7 +573,6 @@ sub24_A_minus_B:
ld (A_m2), a
ret
is_A_mant_zero:
ld a, (A_m2)
ld b, a
@ -567,7 +583,6 @@ is_A_mant_zero:
or b
ret
shr24_A_1:
ld a, (A_m2)
srl a
@ -580,7 +595,6 @@ shr24_A_1:
ld (A_m0), a
ret
shl24_A_1:
ld a, (A_m0)
add a, a
@ -593,8 +607,8 @@ shl24_A_1:
ld (A_m2), a
ret
; Shift B mantissa right by A bits (A=0..255)
shr24_B_by_A:
ld (SHCNT), a
ld a, (SHCNT)
@ -605,10 +619,12 @@ shr24_B_by_A:
ld (B_m1), a
ld (B_m0), a
ret
shr24_B_by_A_ok:
ld a, (SHCNT)
or a
ret z
shr24_B_by_A_loop:
ld a, (B_m2)
srl a
@ -625,17 +641,18 @@ shr24_B_by_A_loop:
jr nz, shr24_B_by_A_loop
ret
normalize_A_mant:
call is_A_mant_zero
jr nz, normalize_A_mant_nz
xor a
ld (A_exp), a
ret
normalize_A_mant_nz:
ld a, (A_m2)
bit 7, a
ret nz
normalize_A_mant_left_loop:
ld a, (A_m0)
add a, a
@ -654,31 +671,33 @@ normalize_A_mant_left_loop:
jr z, normalize_A_mant_left_loop
ret
; ============================================================
; 8x8 -> 16 multiply (unsigned), shift-add
; in: A = multiplicand, C = multiplier
; out: HL = 16-bit product
; ============================================================
mul8u:
ld h, 0
ld l, 0
ld b, 8
mul8u_m8:
srl c
jr nc, mul8u_noadd
ld e, a
ld d, 0
add hl, de
mul8u_noadd:
add a, a
djnz mul8u_m8
ret
; ============================================================
; 24x24 schoolbook multiply into P0..P5 (P0 LSB)
; ============================================================
mul24x24_schoolbook:
xor a
ld (P0), a
@ -753,7 +772,6 @@ mul24x24_schoolbook:
ret
add16_to_P_at0:
ld a, (P0)
add a, l
@ -762,6 +780,7 @@ add16_to_P_at0:
adc a, h
ld (P1), a
ret
add16_to_P_at1:
ld a, (P1)
add a, l
@ -770,6 +789,7 @@ add16_to_P_at1:
adc a, h
ld (P2), a
ret
add16_to_P_at2:
ld a, (P2)
add a, l
@ -778,6 +798,7 @@ add16_to_P_at2:
adc a, h
ld (P3), a
ret
add16_to_P_at3:
ld a, (P3)
add a, l
@ -786,6 +807,7 @@ add16_to_P_at3:
adc a, h
ld (P4), a
ret
add16_to_P_at4:
ld a, (P4)
add a, l
@ -795,11 +817,11 @@ add16_to_P_at4:
ld (P5), a
ret
; ============================================================
; Normalize product P into A mantissa
; P is 48-bit, P0 LSB .. P5 MSB
; ============================================================
norm_product_to_A:
ld a, (P5)
bit 7, a
@ -810,9 +832,11 @@ norm_product_to_A:
inc a
ld (A_exp), a
jr norm_product_take
norm_product_shift23:
ld a, 23
call shr48_P_by_A
norm_product_take:
ld a, (P2)
ld (A_m2), a
@ -822,12 +846,12 @@ norm_product_take:
ld (A_m0), a
ret
shr48_P_by_A:
ld (SHCNT), a
ld a, (SHCNT)
or a
ret z
shr48_P_by_A_loop:
ld a, (P5)
srl a
@ -853,11 +877,11 @@ shr48_P_by_A_loop:
jr nz, shr48_P_by_A_loop
ret
; ============================================================
; Mantissa division (restoring-style)
; A_m = (A_m << 23) / B_m
; ============================================================
div_mantissas_to_A:
; P = A_m as 48-bit, then shift left 23
xor a
@ -881,6 +905,7 @@ div_mantissas_to_A:
ld (A_m0), a
ld b, 24
div_mantissas_loop:
call shl24_A_1
call shl48_P_1
@ -893,18 +918,20 @@ div_mantissas_loop:
or 0x1
ld (A_m0), a
jr div_mantissas_next
div_mantissas_restore:
call add24_Phigh_plus_B
div_mantissas_next:
djnz div_mantissas_loop
ret
shl48_P_by_A:
ld (SHCNT), a
ld a, (SHCNT)
or a
ret z
shl48_P_by_A_loop:
call shl48_P_1
ld a, (SHCNT)
@ -913,7 +940,6 @@ shl48_P_by_A_loop:
jr nz, shl48_P_by_A_loop
ret
shl48_P_1:
ld a, (P0)
add a, a
@ -935,7 +961,6 @@ shl48_P_1:
ld (P5), a
ret
sub24_Phigh_minus_B:
ld a, (B_m0)
ld b, a
@ -954,7 +979,6 @@ sub24_Phigh_minus_B:
ld (P5), a
ret ; carry set indicates borrow
add24_Phigh_plus_B:
ld a, (B_m0)
ld b, a
@ -973,12 +997,12 @@ add24_Phigh_plus_B:
ld (P5), a
ret
; ============================================================
; fp_print: fixed format printing
; Prints: [-]I.FFFFFF (FRAC_DIGITS digits)
; Uses os_print_vec (A=char)
; ============================================================
fp_print:
; zero?
ld a, (hl)
@ -989,6 +1013,7 @@ fp_print:
ld a, '.'
call os_print_vec
ld b, FRAC_DIGITS
fp_print_zf:
ld a, '0'
call os_print_vec
@ -1009,8 +1034,10 @@ fp_print_nz:
jp z, fp_print_ps0
ld a, 1
jr fp_print_ps1
fp_print_ps0:
xor a
fp_print_ps1:
ld (PR_SIGN), a
@ -1032,6 +1059,7 @@ fp_print_ps1:
jp z, fp_print_mag
ld a, '-'
call os_print_vec
fp_print_mag:
; S = (E - 23)
ld a, (PR_E)
@ -1069,6 +1097,7 @@ fp_print_S_nonneg:
cp 32
jr c, fp_print_doShl
ld a, 31
fp_print_doShl:
ld b, a
ld a, (PR_M0)
@ -1086,6 +1115,7 @@ fp_print_print_int_and_frac:
ld a, '.'
call os_print_vec
ld b, FRAC_DIGITS
fp_print_fr:
call mul_remainder_by_10
ld a, (PR_R3)
@ -1096,14 +1126,15 @@ fp_print_fr:
djnz fp_print_fr
ret
; Shift-right PR_INT by B, collect shifted-out bits into PR_R3 (simplified)
shr32_INT_to_INT_with_remainder:
xor a
ld (PR_R3), a
ld a, b
or a
ret z
shr32_INT_to_INT_with_remainder_loop:
ld a, (PR_INT3)
srl a
@ -1125,11 +1156,11 @@ shr32_INT_to_INT_with_remainder_loop:
djnz shr32_INT_to_INT_with_remainder_loop
ret
shl32_INT_by_B:
ld a, b
or a
ret z
shl32_INT_by_B_loop:
ld a, (PR_INT0)
add a, a
@ -1146,7 +1177,6 @@ shl32_INT_by_B_loop:
djnz shl32_INT_by_B_loop
ret
mul_remainder_by_10:
ld a, (PR_R3)
ld b, a
@ -1158,8 +1188,8 @@ mul_remainder_by_10:
ld (PR_R3), a
ret
; Print PR_INT (u32) as decimal
print_u32_dec:
ld a, (PR_INT0)
ld b, a
@ -1175,9 +1205,11 @@ print_u32_dec:
ld a, '0'
call os_print_vec
ret
print_u32_dec_nz:
xor a
ld (DIGLEN), a
print_u32_dec_dloop:
call u32_div10_inplace; remainder in A, quotient back in PR_INT
ld hl, DIGBUF
@ -1205,6 +1237,7 @@ print_u32_dec_dloop:
; print in reverse
ld a, (DIGLEN)
ld b, a
print_u32_dec_pr:
dec b
ld hl, DIGBUF
@ -1218,8 +1251,8 @@ print_u32_dec_pr:
jr nz, print_u32_dec_pr
ret
; Divide PR_INT (u32) by 10, return remainder in A (0..9)
u32_div10_inplace:
ld b, 0; remainder
ld hl, PR_INT3
@ -1232,12 +1265,14 @@ u32_div10_inplace:
call u32_div10_step
ld a, b
ret
u32_div10_step:
; DE = remainder*256 + byte
ld a, b
ld d, a
ld e, (hl)
ld c, 0; quotient byte
u32_div10_div:
ld a, d
or a
@ -1245,6 +1280,7 @@ u32_div10_div:
ld a, e
cp 10
jr c, u32_div10_done
u32_div10_sub:
ld a, e
sub 10
@ -1254,17 +1290,18 @@ u32_div10_sub:
ld d, a
inc c
jr u32_div10_div
u32_div10_done:
ld (hl), c
ld b, e
ret
; ============================================================
; fp_parse: parse decimal string -> float
; DE -> "[-]ddd[.ddd]\0"
; HL -> output float
; ============================================================
fp_parse:
xor a
ld (P_SIGN), a
@ -1282,6 +1319,7 @@ fp_parse:
ld (P_SIGN), a
inc de
jr fp_parse_intpart
fp_parse_chkplus:
ld a, (de)
cp '+'
@ -1292,6 +1330,7 @@ fp_parse_intpart:
ld a, (de)
call is_digit
jr nc, fp_parse_maybe_dot
fp_parse_il:
ld a, (de)
sub '0'
@ -1310,6 +1349,7 @@ fp_parse_maybe_dot:
inc de
ld b, MAX_FRAC
fp_parse_fl:
ld a, (de)
call is_digit
@ -1357,7 +1397,6 @@ fp_parse_apply_sign:
ld (hl), a
ret
is_digit:
cp '0'
jr c, is_digit_no
@ -1365,12 +1404,13 @@ is_digit:
jr nc, is_digit_no
scf
ret
is_digit_no:
or a
ret
; P_S = P_S*10 (uses PR_INT and PR_R0..3 as scratch)
u32_mul10_scaled:
; PR_INT = P
ld a, (P_S0)
@ -1421,11 +1461,11 @@ u32_mul10_scaled:
ld (P_S3), a
ret
shl32_R_by_B:
ld a, b
or a
ret z
shl32_R_by_B_loop:
ld a, (PR_R0)
add a, a
@ -1442,8 +1482,8 @@ shl32_R_by_B_loop:
djnz shl32_R_by_B_loop
ret
; P_S += C (0..9)
u32_add8_scaled:
ld a, (P_S0)
add a, c
@ -1459,8 +1499,8 @@ u32_add8_scaled:
ld (P_S3), a
ret
; Convert P_S (u32) to float at (HL). Positive only; sign handled by caller.
fp_from_u32_scaled_to_A:
ld a, (P_S0)
ld b, a
@ -1502,6 +1542,7 @@ fp_from_u32_scaled_to_A_nz:
ld b, 7
ld a, (P_S0)
ld c, a
fp_from_u32_scaled_to_A_scan:
fp_from_u32_scaled_to_A_find:
bit 7, c
@ -1511,6 +1552,7 @@ fp_from_u32_scaled_to_A_find:
ld c, a
dec b
jr fp_from_u32_scaled_to_A_find
fp_from_u32_scaled_to_A_found:
; EXP = FP_BIAS + B
ld a, b
@ -1546,7 +1588,6 @@ fp_from_u32_scaled_to_A_found:
ld (hl), a
ret
; ============================================================
; BSS / WORKSPACE
; ============================================================
@ -1568,14 +1609,27 @@ B_m1: .space 1
B_m0: .space 1
; 48-bit workspace (P0 LSB .. P5 MSB)
P0: .space 1
P1: .space 1
P2: .space 1
P3: .space 1
P4: .space 1
P5: .space 1
SHCNT: .space 1
P0:
.space 1
P1:
.space 1
P2:
.space 1
P3:
.space 1
P4:
.space 1
P5:
.space 1
SHCNT:
.space 1
; Print temps
PR_SIGN: .space 1
@ -1601,8 +1655,12 @@ P_S2: .space 1
P_S3: .space 1
; Digit buffer
DIGBUF: .space 1
DIGLEN: .space 1
DIGBUF:
.space 1
DIGLEN:
.space 1
; ============================================================
; pow10_table: 10^k constants (k=0..6) in THIS float encoding
@ -1616,6 +1674,7 @@ DIGLEN: .space 1
; 1000000.0= 146 74 24 00
; ============================================================
.section "zone", "acrx"
pow10_table:
.byte 127, 0x00, 0x00, 0x00; 10^0 = 1
.byte 130, 0x20, 0x00, 0x00; 10^1 = 10

67
zone.asm
View file

@ -11,20 +11,87 @@
.global os_inbyte_vec
.global os_main_loop
.set UARTSTATUS, 6
.set UARTDATA, 7
zone_start:
ret
os_print_vec:
; this takes a character in a and sends it to the UART
push af
push bc
push de
ld d, a
ld bc, UARTSTATUS
$1:
in a, (c); get status byte
bit 0, a; test bit 0
jr z, $1; jump back if UART not ready
ld a, d
ld bc, UARTDATA
out (c), a; send byte to uart
pop de
pop bc
pop af
ret
os_getch_vec:
ret
os_outbyte_vec:
; this takes a byte in a and sends it to port in hl
push af
push bc
push hl
ld c, l
out (c), a
pop hl
pop bc
pop af
ret
os_inbyte_vec:
; this gets a byte from port in hl and returns it in a
push bc
push hl
ld c, l
in a, (c)
pop hl
pop bc
ret
os_main_loop:
jp os_main_loop
zoneSignon:
.string "ZONE OS ver. 0.01"
zoneCopyright:
.string "(c) A.M. Rowsell, license MPLv2"
zonePrompt:
.string "z] "
; error messages
errorSyntax:
.string "Syntax error!"
errorTimeout:
.string "Command timed out."
errorNotFound:
.string "Command/file not found."
errorHardware:
.string "Hardware error!"
errorRAMFailed:
.string "RAM test failed!"
stringTable:
.word zoneSignon, zoneCopyright, zonePrompt
.word errorSyntax, errorTimeout, errorNotFound
.word errorHardware, errorRAMFailed