diff options
Diffstat (limited to 'subx/074print-int-decimal.subx')
| -rw-r--r-- | subx/074print-int-decimal.subx | 122 |
1 files changed, 76 insertions, 46 deletions
diff --git a/subx/074print-int-decimal.subx b/subx/074print-int-decimal.subx index 86015a00..04385795 100644 --- a/subx/074print-int-decimal.subx +++ b/subx/074print-int-decimal.subx @@ -6,7 +6,8 @@ # . 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes #? Entry: # run a single test, while debugging -#? e8/call test-print-int32-decimal/disp32 +#? e8/call test-print-int32-decimal-negative/disp32 +#? #? # syscall(exit, Num-test-failures) #? 8b/copy 0/mod/indirect 5/rm32/.disp32 . . 3/r32/EBX Num-test-failures/disp32 # copy *Num-test-failures to EBX #? b8/copy-to-EAX 1/imm32/exit @@ -17,27 +18,30 @@ print-int32-decimal: # out : (address stream), n : int32 # to the stack, before popping them one by one into the stream # # pseudocode: - # copy ESP to EBX - # EAX = |n| + # push sentinel + # EAX = abs(n) # while true - # if (EAX == 0) break # sign-extend EAX into EDX # EAX, EDX = EAX/10, EAX%10 + # EDX += '0' # push EDX + # if (EAX == 0) break # if n < 0 - # push '-' - '0' = -3 - # max/ECX = &out->data[out->length] - # w/EAX = out->write - # curr/EDI = &out->data[out->write] + # push '-' + # w = out->write + # curr = &out->data[out->write] + # max = &out->data[out->length] # while true - # if (ESP == EBX) break + # pop into EAX + # if (EAX == sentinel) break # if (curr >= max) abort - # pop into EDX - # EDX += '0' # convert decimal digit to ascii - # *curr = DL + # *curr = AL # ++curr # ++w # out->write = w + # (based on K&R itoa: https://en.wikibooks.org/wiki/C_Programming/stdlib.h/itoa) + # (this pseudocode contains registers because operations like division + # require specific registers in x86) # # . prolog 55/push-EBP @@ -48,67 +52,63 @@ print-int32-decimal: # out : (address stream), n : int32 52/push-EDX 53/push-EBX 57/push-EDI - # copy ESP to EBX - 89/copy 3/mod/direct 3/rm32/EBX . . . 4/r32/ESP . . # copy ESP to EBX # ten/ECX = 10 b9/copy-to-ECX 0xa/imm32 - # EAX = |n| + # push sentinel + 68/push 0/imm32/sentinel + # EAX = abs(n) 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 0/r32/EAX 0xc/disp8 . # copy *(EBP+12) to EAX 3d/compare-EAX-with 0/imm32 - 7d/jump-if-greater-or-equal $print-int32-decimal:read-loop/disp8 + 7d/jump-if-greater-or-equal $print-int32-decimal:read-loop/disp8 $print-int32-decimal:negative: f7 3/subop/negate 3/mod/direct 0/rm32/EAX . . . . . . # negate EAX $print-int32-decimal:read-loop: - # if (EAX == 0) break - 3d/compare-EAX-and 0/imm32 - 74/jump-if-equal $print-int32-decimal:read-break/disp8 - # sign-extend + # EAX, EDX = EAX / 10, EAX % 10 99/sign-extend-EAX-into-EDX - # EAX, EDX = divide-with-remainder EAX/ten, EAX%ten - f7 7/subop/divide-by 3/mod/direct 1/rm32/ECX . . . . . . # divide EDX:EAX by ECX, storing quotient in EAX and remainder in EDX + f7 7/subop/idiv 3/mod/direct 1/rm32/ECX . . . . . . # divide EDX:EAX by ECX, storing quotient in EAX and remainder in EDX + # EDX += '0' + 81 0/subop/add 3/mod/direct 2/rm32/EDX . . . . . 0x30/imm32 # add to EDX # push EDX 52/push-EDX - eb/jump $print-int32-decimal:read-loop/disp8 + # if (EAX == 0) break + 3d/compare-EAX-and 0/imm32 + 7f/jump-if-greater $print-int32-decimal:read-loop/disp8 $print-int32-decimal:read-break: # if (n < 0) push('-') 81 7/subop/compare 1/mod/*+disp8 5/rm32/EBP . . . . 0xc/disp8 0/imm32 # compare *(EBP+12) - 7d/jump-if-greater-or-equal $print-int32-decimal:write/disp8 + 7d/jump-if-greater-or-equal $print-int32-decimal:write/disp8 $print-int32-decimal:push-negative: - 68/push -3/imm32/dash-minus-zero - # fall through + 68/push 0x2d/imm32/- $print-int32-decimal:write: # EDI = out 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 7/r32/EDI 8/disp8 . # copy *(EBP+8) to EDI - # max/ECX = &out->data[out->length] - 8b/copy 1/mod/*+disp8 7/rm32/EDI . . . 1/r32/ECX 8/disp8 . # copy *(EDI+8) to ECX - 8d/copy-address 1/mod/*+disp8 4/rm32/sib 7/base/EDI 1/index/ECX . 1/r32/ECX 0xc/disp8 . # copy EDI+ECX+12 to ECX - # w/EAX = out->write - 8b/copy 0/mod/indirect 7/rm32/EDI . . . 0/r32/EAX . . # copy *EDI to EAX - # curr/EDI = &out->data[out->write] - 8d/copy-address 1/mod/*+disp8 4/rm32/sib 7/base/EDI 0/index/EAX . 7/r32/EDI 0xc/disp8 . # copy EDI+EAX+12 to EDI + # w/EDX = out->write + 8b/copy 0/mod/indirect 7/rm32/EDI . . . 2/r32/EDX . . # copy *EDI to EDX + # curr/ECX = &out->data[out->write] + 8d/copy-address 1/mod/*+disp8 4/rm32/sib 7/base/EDI 2/index/EDX . 1/r32/ECX 0xc/disp8 . # copy EBX+EDX+12 to ECX + # max/EBX = &out->data[out->length] + 8b/copy 1/mod/*+disp8 7/rm32/EDI . . . 3/r32/EBX 8/disp8 . # copy *(EDI+8) to EBX + 8d/copy-address 1/mod/*+disp8 4/rm32/sib 7/base/EDI 3/index/EBX . 3/r32/EBX 0xc/disp8 . # copy EDI+EBX+12 to EBX $print-int32-decimal:write-loop: - # if (ESP == EBX) break - 39/compare 3/mod/direct 4/rm32/ESP . . . 3/r32/EBX . . # compare ESP and EBX + # pop into EAX + 58/pop-to-EAX + # if (EAX == sentinel) break + 3d/compare-EAX-and 0/imm32/sentinel 74/jump-if-equal $print-int32-decimal:write-break/disp8 # if (curr >= max) abort - 39/compare 3/mod/direct 7/rm32/EDI . . . 1/r32/ECX . . # compare EDI and ECX + 39/compare 3/mod/direct 1/rm32/ECX . . . 3/r32/EBX . . # compare ECX with EBX 7d/jump-if-greater-or-equal $print-int32-decimal:abort/disp8 - # pop into EDX - 5a/pop-into-EDX - # EDX += '0' - 81 0/subop/add 3/mod/direct 2/rm32/EDX . . . . . 0x30/imm32/zero # add to EDX $print-int32-decimal:write-char: - # *curr = DL - 88/copy-byte 0/mod/indirect 7/rm32/EDI . . . 2/r32/DL . . # copy DL to byte at *ECX + # *curr = AL + 88/copy-byte 0/mod/indirect 1/rm32/ECX . . . 0/r32/AL . . # copy AL to byte at *ECX # ++curr - 47/increment-EDI + 41/increment-ECX # ++w - 40/increment-EAX + 42/increment-EDX eb/jump $print-int32-decimal:write-loop/disp8 $print-int32-decimal:write-break: # out->write = w - 8b/copy 1/mod/*+disp8 5/rm32/EBP . . . 7/r32/EDI 8/disp8 . # copy *(EBP+8) to EDI - 89/copy 0/mod/indirect 7/rm32/EDI . . . 0/r32/EAX . . # copy EAX to *EDI + 89/copy 0/mod/indirect 7/rm32/EDI . . . 2/r32/EDX . . # copy EDX to *EDI $print-int32-decimal:end: # . restore registers 5f/pop-to-EDI @@ -166,6 +166,36 @@ test-print-int32-decimal: # . end c3/return +test-print-int32-decimal-zero: + # - check that 0 converts correctly + # setup + # . clear-stream(_test-stream) + # . . push args + 68/push _test-stream/imm32 + # . . call + e8/call clear-stream/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 4/imm32 # add to ESP + # print-int32-decimal(_test-stream, 0) + # . . push args + 68/push 0/imm32 + 68/push _test-stream/imm32 + # . . call + e8/call print-int32-decimal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 8/imm32 # add to ESP + # check-stream-equal(_test-stream, "0", msg) + # . . push args + 68/push "F - test-print-int32-decimal-zero"/imm32 + 68/push "0"/imm32 + 68/push _test-stream/imm32 + # . . call + e8/call check-stream-equal/disp32 + # . . discard args + 81 0/subop/add 3/mod/direct 4/rm32/ESP . . . . . 0xc/imm32 # add to ESP + # . end + c3/return + test-print-int32-decimal-multiple-digits: # - check that a multi-digit number converts correctly # setup |